Sci Fi
2085 Warlord of the Wasteland
A project initially conceived in dissatisfaction of the way things were. For modern or post/apocalyptic miniatures gamer.
40K Advanced Rules
Intended for veteran players who have a firm understanding of the current 40k rules. Army balance issues may come up, but war isn’t fair.
A Fistful of Tripods
A set of miniatures wargame rules to fight battles from H.G. Wells' The War of the Worlds. The system is the tried and true A Fistful of TOWs system and is designed for fast play.
A Sky Full of Ships
A simple (but not too simple) set of starship combat rules, which allow huge fleets to engage each other in epic battle (and finish in a reasonable amount of time).
Admiral
In essence ADMIRAL is a game of strategy and luck in which you attempt to manoeuvre the greater fire power of many ships against the weaker shields of a single ship.
Afterglow
Skirmish warfare in the Far Future Craig Cartmell.
Alien Empires
Board Game. Is your alliance of alien races the strongest?
Alien Invasion
This is a skirmish level game designed to be played by four to six players in about an hour and a half. Each player will control a competing faction with personal victory conditions to achieve based on the scenario chosen. The fate of the Earth hangs in the balance.
Anaxis
A tactical space wargame, using ship counters and hex paper. It's moderate in complexity and detail.
Anteel
A rules-light but tactically serious space wargame, which is completely diceless - in fact there are no randomizers of any kind, resulting in a game that is all about strategy, rather than luck.
Astral Dreams
This Miniature game is based off of the story Astral Dreams (copyright 2002 C. Gerard Luft). The game mechanics herein are derived from the Open Gaming License of the D20 Systems Reference Document.
AT-43
A science fiction tabletop wargame using 28 mm miniature figures and terrain to scale developed and published by Rackham.
Basic Space Ship Rules
A simple set of rules for Imperial Cruisers in the Star Wars universe.
Battle Platform Antilles
A solitaire game, you have an elite squadron of Paladin Class assault ships are under your command. Objective: Destroy an artefact battle platform while minimizing losses to your squadron.
Battlefleet Gothic
Games Workshop now publishes the Living Rulebook on the web.
Battlefield Evolution
Battlefield Evolution is a fast-paced and easy to learn miniatures game, with enough tactical depth to keep you hooked for years. You will command small forces based on real world armies of the near future.
Battleshift - Space Fleet Combat
Battleshift was born in a thread on The Miniatures Page. People were looking for a fast, enjoyable space game that would let them field real fleets. Not like a dozen ships, but scores or hundreds of ships.
Battlestar Galactica: Colonial Battlefleet 2nd Edition
This is a fast play starship combat game played at the individual ship level at the scale of small task forces. Fighter squadrons are represented by single models. The rules were designed to be taught and played in a convention environment and are very easy to learn. Mastering the strategy, however is something else entirely.
Battlestar Galactica Mass Combat Game
This game is designed to be played with lots of ships; each ship is represented as single figure. This game is designed so each player should be able to control 10-20 Star fighters with out any problems. My goals are that there should be no paper work involved, and a minimum of markers or counters used.
Beamstrike
Beamstrike is a fast paced war-game set in the far future. Battle with human forces, Aliens, and Androids using a multitude of weapon systems. Rules for vehicle use and Fire support are included. Generic background provided, but may be used with whatever background you want. 
Beneath The Waves
A set of fast play rules for Steampunk submarine combat. Can be played as a boardgame or a miniature game. 
Big Burn
These rules are designed for a player to control several capital ships in a major fleet action. They were designed to allow players to refight the huge space battles of the Exterminator War.
Black Skies
Generic Star Fighter Combat Rules. Quick and simple rules intended to create a fast moving star fighter game, where out thinking your opponent is as important as out shooting him. Games can be as small as single fighter duels, all the way up to entire squadrons being used in a multi player campaign.
Blasted Planets
Lance Runolfsson's Blasted Planets Skirmish game rules. Not hard environment set of Sci Fi rules.
Boots, Tracks and Hovercraft
Operational-level wargame for the 2300AD game universe
Bugged
It is a Hex-based wargame that uses cards to add spice to what units can do.
Bug Hunt
Upgraded version to Is This Just Another Bug Hunt rules.
Bugs
SF Ground War Rules for Inter-Species Combat - especially Starship Troopers.
Bugs!
An easy to play miniatures game where the bugs are big with an attitude and it's your job to turn them into pink mist before they slice and dice you. Man against bug at the personal level.
Bugs Don't Surf
This is the name of the Stargrunt II alien supplement, as mentioned in the back of the SG2 rule book.
Cap'n Arjun's Starship Rules
Command one or more starships in fast-and-furious tactical space combat.
Chain Reaction (Old School)
Sci Fi rules from Two Hour Wargames. The old version of the rules are available free.
Chain Reaction 3
All the latest mechanics currently used by the THW regular games like 5150, All Things Zombie and the rest.
Classic BattleTech Quick Start Rules
Shortened version of the BattleTech rules to play with a basic mech.
Combat Action
For 25 to 33mm miniatures. The rules cover anything from skirmishes with a dozen or so models per side to conflicts with multiple squads, vehicles and support weapons.
Command Horizon
A set of wargames rules allowing players to stage battles and conflicts set in Human Space in the mid years of the 26 Century. Support can be found at Command Horizon the home of the miniatures. Now at version 4.1.
Conflict of Worlds : Generals
Based in a 21st Century where you can control a combination of 133 formations. The combat system uses the Epic Armageddon engine with a lot of tweaks and adjustments. Templates and objectives. City Sectors.
Crimson Dusk
A ruleset that allows you to take whatever models you have in your collection, in any scale and use them in wargames.
Crimson Dust
A skirmish game using mutliple D6 rolls to establish the results of shooting moving, etc. Its also a turnless game with players activating models or using a leader groups of models in sequence.
Cruel Void
This is about space dogfighting. It has little, if anything, carried over from our previous science fiction space battle system, Final Frontier.
Dam'd Star Ships Again
This set of rules is based, very loosely on the Dam'd Battleships Again, a free set of rules by Phil Barker which covers naval warfare at the start of the 20th Century, before the advent of Dreadnaught.
Damn the Torpedoes
Sci-Fi wargaming using Silent Death rules and tabletop miniatures.
Dark Millenium
Open Source rules which can be used with Games Workshop 40K Figures.
Dark Realm Miniatures Rules
Version 2.5 of DRM 6mm Sci Fi rules. The rules includes everything you'll need to get your armies into action. As well as the core rules and mechanics the file also includes counters and area of effect blast templates.
Dead Run
A set of science fiction wargame rules for worlds that are hard, fast and deadly, and you need to be the same.
Death Racers
Mad Max style post-apocalyptic gang-warfare road combat.
Death to the Alien Scum
A 6mm Invasion Earth Battlegame.
Defiance
The Defiance Universal Skirmish System the game of near future and science fiction tactical combat that lets you modify or even create the strategic setting in which your battles will take place.
Dirtside II
Ground Zero Games rules now free download. Rules cover armour, infantry, artillery, combat walkers, and aerospace support forces. The "fast play" combat system is chartless.
Dr Who Miniatures Game
An attempt to recreate the drama of the Doctors many adventures on a tabletop using miniatures.
Dreadnought Arena Combat
Dreadnought Arena Combat (DAC) is meant to be a fast and furious multi-player game that can be completed in a little over an hour.
Dropship Horizon
Sci Fi gaming using 15mm figures.
Drop Troops
Futuristic Tactical Miniatures Ruleset. Each player controls a squad of heavily armed Drop Troopers (Space Marines).
Earth: Reborn
Earth is destroyed and the survivors must fight for their right to survive.
Easy Star
Starship design and tactical battle. Easy to learn, but dozens of options keep the game from becoming predictable. 2-4 players.
Emporex
Strategic conflict for 20 planets. Unique units.
Enclave
Aftermath scenario. Recruit mutants and Scavenge guns.
Epic
Epic is the game of mass combat set in the nightmare future of the 41st millennium. These are not simply the battles of man against man. Epic battles feature immense armies of infantry, legions of tanks and giant war engines such as the bipedal Titans and super-heavy tanks armed with weapons normally seen on starships.
Epic Escarmouches
An original game system based on the Space Marine and Epic 40k. Uses mainly single Epic infantry figurines. In French and English.
Event Horizon
Quick Play Star Ship Combat Rules version (includes campaign rules).
Expansion
A modification of Ian Shaw's Steer for the Third Planet on the Left tactical spaceship combat rules and a campaign system to go with them.
Extermination and Survival
Rules For "Extermination and survival" a sci fi combat game similar to starship trooper movies. Join the yahoo group to get the rules.
F.A.D.
Generic set of scifi skirmish rules. Focus on realism and troop quality. Has its own background but can be used for any setting.
Factions
Factions is a squad based game of warfare between rival gangs. Factions is similar in many way to a plethora of Games Workshop games (because that is what we based it on). 
Faction Wars
Set in the Inviroate Commonwealth of the Federated Worlds sometime in the 23rd century. Choose a faction, kit your squad out with weapons, armour and special skills, and then try to outdo your opponent on the battlefield. 
Fallout Warfare
Fallout Warfare (FOW) is a paper and pencil wargame set in the Fallout universe. Based loosely on the Fallout Tactics game, FOW allows you to recreate small to medium sized skirmishes in the Fallout post-nuclear world.
Fast Play Fleets - Star Trek
FPF came into being because the author could not find a system that allowed him to fight his Federation V Klingons the way he'd seen in films.
Fate and Destiny
Fate and Destiny are a set of miniature rules for sci-fi combat in the 30th century. Fleet combat including fighters, missiles, grappling and boarding are covered.
Fearless
Fearless is a fast-paced science fiction tabletop game including role-playing elements. In a universe of limitless possibilities you can lead various mercenary characters through fierce battles in the arena.
Firefight
This games system was firstly written as a simple game to be used primarily in conjunction with Alternatives Armies 15mm Sci-fi Firefight miniatures range though it has become far more, now being a generic system. Army lists available too.
Firefight 2050
A set of rules for 1/72 figures in a near future setting.
Flotilla
Starship Combat on a massive Scale.
Forge of War
This set of rules is born of frustration with Games Workshop and Warhammer 40K. Second Edition.
Formula Ace Racing Pods (English)
Race your pods like Luke Skywalker.
Formula Ace Racing Pods (French)
Race your pods like Luke Skywalker.
Frag Bughunt
Frag Bug Hunt is based on the original Frag boardgame rules and Jeremehovah's Aliens Vs Predator variant.
Frag-o-rama
Frag-o-rama is the free miniatures game of multi-player, shoot-‘em-up, videogame-style action for 2 to 10 players. 
FUBAR
One page Modern/SF small unit action rules. Supplements now available. 
Full Thrust 1889 : Mercury Misery
Full Thrust conversion for Frank Chadwick's Space: 1889.
Full Thrust 2
The complete second version of the classic Full Thrust rules. Now available for free.
Full Thrust Cross Dimensions
This is not the third edition. Cross Dimensions is a variant, a different version produced with the kind permission of Ground Zero Games.
Full Thrust: Fleet Book 1
This is the first volume of two Fleet Books, to provide players with a resource of pre generated ship designs that tie in with the GZG ranges of Starship Miniatures. Human Forces.
Full Thrust: Fleet Book 2
This is the second volume of two Fleet Books, to provide players with a resource of pre generated ship designs that tie in with the GZG ranges of Starship Miniatures. Alien Forces.
Full Thrust: More Thrust
Expansion rules for Full Thrust.
Full Thrust Lite
The simplest core rules of the game brought up to the current standard (2.5) there are a couple of little tweaks that veteran players will spot, but no major changes. It has been written as an ideal introduction to the system for new players, and we hope it will be especially useful for getting younger players into the game.
Full Thrust Star Wars
Conversion for Full thrust of the Star Wars genre. Download Main Stats and Star Destroyer
Future Wars
Control a small band of elite warriors who want to either destroy the Kingdom of Evil or help it conquer the universe.
Futuristic Fast Tactics Tabletop (FFTT)
FFTT is a sci-fi tabletop game based on infantry skirmishes between two players in its closest and fastest version. Rules still testing.
Galacta 3
Man-to-man tabletop miniatures game in 25mm scale. The rules are simple and fast to learn, and all actions can be resolved by the roll of a single 12-sided die.
Galax
Set Piece abstract Spaceship combat. Written orders to move and fire. Ship design.
Gang Warfare
Build your 'Gang', set up businesses, take over the block.
Gemini Rules for Warhammer 40,000
Alternate rules are inspired by those in WH40K-RT or 3rd Ed with some stuff from the 4th Edition.
Generic Space Combat 2
The Next Generation of Starship Combat.
GOBS
Generic Outlandishly Big Spacefleets! They're customizable, flexible, fast, simple and require little record keeping. They'll work with any miniatures, scale or basing scheme.
Green Blood and Red Blood for Mars
Martians, Indunas, Colonels and Emirs was originally published to cover tactical mass warfare on Mars during the Victorian Science Fiction Era of the late 1800s. Units with twenty men as well as those with 500 men can be represented on the board.
Grim Future
Simple skirmish rules for Science Fiction Infantry warfare.
Grind
The merciless sport of Grind is getting set to hit the grid this October. Prepare yourself for the most brutal sport ever created.
Ground War 3000
Set Piece battles. Many units, Ground/Air/Sea, Nukes.
Guerilla
A skirmish rule for science fiction or fantasy miniatures in French.
Hammers Slammers
Sci Fi Rules for re-enacting the David Drake book of the same name.
Hammers Slammers Sci Fi Skirmish
Generic rules, they can be used to produce Aliens games and to recreate skirmish fights from the "Hammers Slammers" books.
Hellfire
This is about space battles in the far future. It has little carried over from our previous science fiction space battle system, Final Frontier, except, perhaps, the idea of a power allocation system.
Heresy
Mass combat rules on an Games Workshop's EPIC scale, designed by Peter Ramos.
High Crusade
Simple Quick Play SF Rules designed to allow you to play Science Fiction wargames with either 15mm or 25mm scale miniatures.
HOTT for Sci Fi
An adaptation of Hordes Of The Thing to Science Fiction while retaining the simplicity and spirit of the original rules.
Hostile Stars
The core rules. These outline the turn structure and basic gameplay, and concentrate on the basics of pushing model space ships across a table, providing the basic structure of the game and allow players to take the miniatures and do battle. 
Imperial Mars
Victorian Science Fiction, the Author's long time passion for science fiction generated these rules. He wanted a set of rules for the "British on Mars" which was something larger than a skirmish and was freely expandable to include new weapons, races and devices. 
Imperium Battles
A tabletop game for 25mm sci-fi miniatures from the Warhammer 40,000/Mutant Chronicles and similar universes. Based on the old MB/GW 'Space Crusade' game rules.
Infestation
A Warhammer 40,000 Game of Zombies.
Infinity
Infinity is a futuristic universe, shaped and controlled by secret and clandestine operations. Well, the moment has come for those operations see the light. The moment has come for Infinity Tournament.
Iron Cow
These simple rules should allow you to create relatively large land battles, pitting armoured companies and infantry battalions against each other. This article is the seed from which the Iron Cow rules grew, now published by Wessex.
Iron Warriors
The setting is an alternative II World War, where the Germans rescue the technology of a flying saucer fallen in Lithuania in 1943. A commercial version will be available in March 2010.
Is this Just Another Bug Hunt
A set of Rules for refighting the Aliens films by Pete Jones. Hunt the bugs down with your trusty colonial marines.
John Companies Men
A new set of skirmish rules under development by Ian Shaw for the SF genre. You must join the yahoo group to access the files. 
Judge Dredd Miniatures Game
These rules are, and always will be free to download. Judge Dredd is a 28mm skirmish game designed to be quick, easy to learn, and capable of handling the madness that is Mega-City One, from the powerful judges to the lowliest punk or mutant. 
Jump Trooper
Fast playing, "hard" Sci-Fi skirmish rules.
Kill Zone
Nick Lund & Hugh Pitt's Near Future skirmish rules (formerly published by Grenadier). 
Kryomek
The complete Kryomek basic rulebook. Now available for free download. The entire Hivestone expansion book available too. 
Landships of Mogdonazia
A homemade scientific romance add-on for The Sword and The Flame. Rules for building your own landships that should synchronise perfectly with TSATF.
Launch Fighters
A new spaceship board game. You can design your own fleet of starships and challenge your opponents in an exciting star battle.
M.A.D.
Fast Play Mechanised Warfare Rules, With Additional Supplements For Aircraft and Future Wars.
Mars or Die
The French Foreign Legion and others on the Red Planet. A Victorian Science Fiction Miniature Figure Game.
Martian Empires
Victorian SF Rules based On Huzzah. Join the yahoo group to download.
Mayhem: Wasteland Warriors
Set in the apocalyptic near future, Mayhem: Wasteland Warriors is man to man combat at it's finest.
Meatbox Massacre
Squeeze inside the squishy cockpit of your genetically engineered war machine! Engage in televised gladiatorial combat between giant bio-robots! Literally devour your enemies! 
MechWarrior
The original Mechwarrior rules from Wizkid. Includes the Special Equipment and the FAQs. 
MekaTac
Set piece Giant Robot tactical combat. Mech design rules.
Meks and Mercs
A simple game for mechs on the tabletop.
Minimal Mech Combat
Saturday morning cartoons, comic books, and transforming toys - Big, powerful robots have been the staple of all three for years. Minimal Mech Combat (MMC) is a simple game that attempts to create the feel of combat between these mechanical warriors.
Minimal Space Combat
The premise behind this game is this: what is the simplest playable game possible to game tactical space combat. The emphasis in this game is fast and easy.
Minimal Tank Combat
Minimal Tank Combat is a simple game that creates the general feel of tank combat, with a slight emphasis on a futuristic setting.
Mobile Infantry
Play Starship Trooper type games by Craig Cartmell.
Mobile Soldier In Action
These rules were meant to be used with the Mobile Suit Gundam "Mobile Suit in Action" action figures, or with 1/144 scaled mobile suit models. The main focus of these rules is The One Year War era.
Mobile Suit at WAR
An original Miniatures Wargame using Bandai's excellent "Mobile Suit in Action" figures.
MuTaTioR Le choc des MuTaNs
Mutants gladiator build by madness professor are engaged in battle for gold and glory. You can build your own mutant as you wish (FRENCH).
Necromunda
Necromunda is a game of fierce combat between rival game fighters in the dangerous underworld of the Necromundan hives. Gangs must fight to gain territories, wealth and renown.
NetEpic
The latest in the long line of NetEpic games, NetEpic v4 for your gaming pleasure. A rewritten EPIC scale game based on the Second Edition Space Marine boxed game.
NetEpic Gold
The ultimate version of NetEpic.
No Frontiers
A "raw" set of rules for spaceship combat which were originally devised for Star Trek Micro Machine models.
No Future
No Future is a skirmish game representing battles between small gangs on the inner city streets of a lawless tomorrow. It gives a playable, fun skirmish game, allowing for an element of roleplay.
No Limits
Generic Sci Fi rules for any background or figure you already have. Ideal skirmish rules.
Now This Is Pod Racing
You saw the game demoed and now you want to play it. Remember, this game is free. You are NOT to sell it in ANY way. It is purely for the enjoyment of Star Wars movie fans.
Nuclear Renaissance
Nuclear Renaissance is a tabletop skirmish game. The rules are for skirmish campaigns in a post apocalyptic wasteland. Players collect a gang of hardened fighters and souped up vehicles from the customisable range of parts and characters.
On The Bounce
A new set of SF rules about hovertank combat in the 21st century. Still under development, and will be updated from time to time.
Orbital Battle
2-player space/land battle. Fight over planets that move in their orbits, changing the game map each turn. This is a complete game with maps and counters.
PacWar
Large scale dogfighting between flights and squadrons of space fighters.
Phaser Lock
Starship Tactical Combat is a miniature-based wargame based on Gene Rodenberry's "Star Trek" as depicted in classic television series and it's subsequent feature films and spins-offs. Join the yahoo group to download.
Phoenix Command
This latest incarnation of Phoenix Command Miniatures builds upon the foundations of the Aliens, Terminator 2, and Blasteroo rules, while still cleaving to the standards set by the Phoenix Command Small Arms Combat System.
Plan A
Divisional level combat
planetside, suitable for 1/300 models or counters.
Plasma Storm
Sci Fi version of the Red Storm (Modern) and Lightning War (WW2) rules for small scale miniatures with several bases representing a battalion.
Point of No Return
Set piece battles, spaceship tactical combat, Fuel and Inertia, Ship design.
Powerspike
The No Dice Science-Fantasy Battle Game.
Prophecy of War
These rules are designed to fill a gap in the Science Fiction wargaming rules market for 6mm. A set of rules that copes with a large amount of models. Can handle 6 players each with 50 plus models. These were published on the web about 5 years ago and rescued here. Download Playsheet and counters to compliment the rules.
Pz8 SciFi
2 page rules for 6mm figures based on Mechanized Warfare Rules.
Quickfire 2
QUICKFIRE acts as a "Rosetta Stone". It provides an environment where any miniature can be used. The designers are both United States Marine Corps Officers.
Red Chicken Rising
A set of tactical spaceship wargame rules set in the Generic Legions universe. This game is intended for use with whatever spaceship miniatures you have available, any size, any scale, any style, from any manufacturer.
Ripped In Space
Spaceship rules with ideas taken from various rule sets.
Road Warriors
Wargames rules for battles between rival car gangs in a post apocalyptic future.
Rollerball
If you enjoyed the original Rollerball film, you’ll also enjoy this re-creation of the exciting sport as a board game. By George Duff.
Rules Crusade
Comprehensive tabletop rules using the classic MB Games board game Space Crusade.
S.L.O.B.S. Simple Large Outer-space Battle System. 42 ships per side (10 ship types) plus fighters. Simple combat, no record-keeping, large-scale mayhem.
Sci Fi Skermish
Sick of the expense and complexity of Warhammer 40K the Rabbidgerbal designed 1PG simple sci-fi rules with rolls for defence that mean not only are defending players more active but a strong figure can have a weak moment.
Sci Fi Skirmish
Sci Fi land Skirmish Rules suitable for the "Hammers Slammers" or similar universes.
Sci Fi Strat
A multi player hex miniature game.
Sci Fight
A simple set of 25mm Science Fiction skirmish battle rules, where one miniature represents one individual. They are intended to be fast and furious with no bookkeeping. If you're hit, you're out!
Seeds of War
6mm Sci Fi Mass Combat rules and setting. 3 army lists are available Andrayada , Pax and Krayatonian.
Senator Arjun's Star Wars Skirmish Rules
Each player controls one or more squads in the Star Wars Universe. 
SGII For Warhammer 40,000
An attempt to get 40K working with a different ruleset, GZG's Stargrunt. 
Shattered Verse
A 15mm Sci Fi Commercial Wargame, These are a free quick start version of the ruleset. 
Shell Shock
A fast playing, adaptable and robust wargame system. It brings the flavour of war to a tabletop game. All the action, all the fury, all the tactics and chaos, in a system that's easier to learn, more intuitive, and more fun to play, than any other wargame on the market today.
Silent Dark
Silent Dark was a commercially-released title- a traditional miniatures wargame set in the 25th Century. It has an extremely flexible rules system that is easily converted to many genres, and the expanded version of the Design System is made for people wanting to play everything from Super Heroes combat to Fantasy.
Slammer
25mm skirmish Sci fi rules (includes bug-hunts/aliens).
Small Spacecraft Combat Rules
The following rules are a modification to Jeff Freeman's starship design rules, intended for creation of smaller fighter craft, typically with a crew of less than five.
Sol Cruiser
A space combat game that combines the basic paradigm of 2300AD's Star Cruiser (emphasis on stealth, detection, and long-range missile fire), Triplanetary-style vector movement, and a ship design system loosely patterned after Full Thrust.
Solar Wars
Space fleet battles. Easy to play by Pete Jones.
Soluna
A one or more player science-fiction wargame in a classic Space Opera setting with strong influences of 1920-30s Art Deco and Art Nouveau.
Space Base
Rival colonies compete for space and revenue.
Space Cruisers
Very simple space ship combat.
Space Fury
Set piece battles Fighter tactical combat. Ship design rules. Pilot skills, quirks, and cool.
Space Insurrection
Recruitment.Very stylized unit interactions.
Stalker: Oblivion Lost
A skirmish game for 28mm set in a science fiction/post apocalyptic setting. While players will command multiple troops, the focus is more on individual figures, equipment and abilities, than large scale combined arms battles.
Starcraft Tactical Miniatures Combat
A game of skirmish-based combat set in the Starcraft Universe. Command small bands or small armies of soldiers, machines, aliens and more into battle against enemies to totally obliterate them as you shoot them, engage into close combat with them, blow them up, and more in this game of total war and destruction. 
Star Crashers
A friendly game for 2-4 players, ages 8 and up. Each turn, players move their spacecraft around the table, exploring by flipping over Blip Counters that could be Space Pirates, Gravity Mines, Derelict Ships, and stranger things. 
Star Cruiser Lite
Heavily reworked Full Thrust rules adapted to 2300AD space combat. New turn sequence, movement systems, detection rules, crew quality rules.Also contains ship conversion rules and selected ship conversions.
Star Frontiers
Digitally Remastered versions of the Star Frontiers RPG and companion books.
Star Frontiers: Knight Hawks
Tactical Space Combat game to tie in with the Star Frontiers RPG, can be fought as a separate tabletop game Quick Reference sheet.
Star Marines
Futuristic land warfare inspired by [that game from GW], but faster and much less expensive. Choose a race, buy armies and weapons, then wage war! This is a complete game with maps and counters. 2 players.
Star Wars Galactic Heroes
A simple tabletop game for Star Wars action figures.
Star Wars - Silent Death
Erik A. Dewey's article "Get to Your Ships" in issue 5 of Star Wars Gamer lets you play the Star Wars Silent Death ship-to-ship combat game in the Rise of the Empire era.
Star Wars Mass Combat Rules
These rules represent an attempt to provide structure to large-scale combats that may occur within a Star Wars RPG scenario.
Star Wars Miniatures Mass Battles Conversion
These rules are not meant to be a wargame/simulator, but a way to play large battles using the established Wizards Star Wars Miniatures system.
Star Wars Shoot Out
Simple Star Wars game.
StarForce
Merging ShockForce rules with Stargrunt II. These rules recently disappeared from the web but now rescued by freewargamesrules.
Stargate
Rules for the Film and TV Series of Stargate. Rules written by Stargate Gamers Yahoo Group. Its free to join and there are some lively discussions on gaming this genre.
Stargate Fleet Command
The goal of this game is to allow players to model ship to ship combat in the Stargate Universe.
Stargate DOW
These rules are a modification of Dogs Of War rules to play Stargate SG teams vs Goa'uld and Jaffas.
Stargrunt II
These skirmish Sci Fi rules are now available as a free download from Ground Zero Games. QRS and Counters.
Starmada - Demo
Starmada is a simple (but not simplistic) board game of starship combat, in which players square off in a general attempt to blast each other's fleets into just so much space junk.
Starship Marine
Starship Marine Streamline is all about the boarding and capturing enemy starships or bases. The original rules for starship boarding action, easy to play, but tactically challenging.
Starship Troopers
A set of quick play rules for board or miniature play of a wargame based on the movie "Starship Troopers".
Starship Troopers(2)
A set of modifications to the Shock Force rules by Demonblade, based on the film by Paul Verhoeven. The rules are based on the film, not the book.
Starship Wars
Space Wars is designed for small scale starship fights but can be used for large scale fights as well. The game design offers several optional rules to make combat more realistic and more powerful.
Starwar 2250
Rules for Starwar 2250 and its rules for starship construction. This an older game with a 1970's miniature game feel so try it out.
Steel Crush
A miniatures game depicting ground combat in the late 22nd century. The game is hex-based. Units represent platoons of 3-5 tanks.
Steel Rain
In depth rules for 1/300th Sci Fi rules. The author is still expanding them.
Steer for the Third Star on the Left
Science Fiction rules for spaceship battles.
Steer for the Third Star on the Left: Campaign Rules
Campaign rules for Steer for the Third Star on the Left.
Stellar Empires: Fleet
This game has been designed and created to provide the player, with the most all-inclusive starship combat game ever produced. The game includes a powerful construction system. Playtest Version, comments can be emailed here.
Stellar Wars
An introductory game of tactical space combat between fleets of space battleships by Tim Swenson.
Stratastar
Space Empires collide, Recruitment, Fast gameplay.
Street Fight Rules
Street fight is a fast and simple rules set for games involving small units or single figures. games should be short and simple and not more than an hour long in most cases. 
Sub Wars
People fight out wars and skirmishes in the near future. These are fought underwater between submarines. 
Tac Ship
A simplified fast-play rules system for simulating combat between manned space fighters. The game may be played on a hex grid map or on a plain table area.
Taktika
Fast and greasy 25mm space rules.
Task Force Zeta
Task Force Zeta allows you to fight battles against opponents in a representation of real(3-D) space using vector movement - without doing complex math every time you move or fire.
Teeny-Weeny Taktika
Fast, detailed and easy way to play space miniatures. For 5mm-15mm figs. Pull out those old Games Workshop Epic miniatures.
The Colonel's Boiler Plated Brandy Snifter
Homebrew add on rules for Chain Reaction covering the Victorian Sci Fi period.
The Iron Frontier
Landship battles of the Steam Age.
The Outer Rim
Starship Battles that includes fighters. Easy to play and a large number of ships can be used. Includes optional weapons by Pete Jones.
Toe To Tow
Sci Fi rules for the GW universe, in the near future.
Trenched
This is a squad-level combat system for miniatures (15 to 30 mm or so).
Tripods and Hussars
A miniatures game focusing on the "historical" Martian invasion of England in 1900. Different system than A Fistful of Tripods.
Turn or Burn
A fast-paced game of space fighter combat for 2 to 8 players. To start a game, you design your fighter from a deck of system cards.
Uber
French rules for Weird War II figures.
Unbreakable
A game of futuristic ground combat for 2 players. Each player assembles a platoon of crawlers, walkers, and powered armor squads and equips them with nukes, stasis rays, lasers, and more.
Universal Soldier Extreme
A set of rules for skirmish level miniature gaming using Rafm Miniatures. The focus of the main rules is on the modern era and optional rules are provided to suit any genre ranging from horror, to pulp fiction, to historical combat.
Urban Myth
Urban myth is a game of the near future set in the United Kingdom. Think cyberpunk but with much more subtlety, pistols where you would find SMG’s etc. This game was inspired by the Greg Mandel books written by Peter F Hamilton.
Urban Warzones
Near-future urban combat rules for firefights between units from Squad right up to Company level.
Vector 3
A 3D space combat board game; its virtue is that players learn the
essentials of vector arithmetic and Newtonian mechanics by playing. Once commercial now released as free by the author.
Vector V5
Vector V5 is a game of combat between small, fast starships in the distant future. The emphasis in creating these rules has been to provide players with a fast exciting game after a game or two, players will probably not have to refer to the rules at all.
Verdammnis Weird WWII Rules
These rules are a modification of Dogs Of War rules to play weird adventures during WW2. 
Vortex
A customizable miniature skirmish game that can be used with any miniature in any setting using the miniatures and terrain you already own. 
WarEngine
Skirmish rules from the once commercial system as presented in Shock Force Second Edition published by DemonBlade Games in 1999 with Shock Force specific material removed.
Warhammer Star Trek
These are a complete set of rules that allow players to fight battles in the Star Trek universe using the Warhammer 40K rules (with or without a few modifications).
Warrior Races of Mars
Martian Warbands vie for Dominance.
Wastelands
Warfare in the post-apocalyptic world. There are over 20 factions to choose from and numerous character archetypes, full rules for battles, mutants, vehicular combat and a simple but satisfying campaign mode. Easy to learn and fast to play with enough depth to give you years of quality gaming. 
Wehrmacht 47
Rules for a what if the German Wehrmacht survived to 1947. They are a supplement for the GHQ micro armor rules. 
Wildfire
A generic ruleset for 15mm science fiction skirmishes (the rules are easily adapted for other scales). Employing a simple and intuitive yet tactical counters-based system with full rules for infantry and vehicles, Wildfire includes a complete design system to let you create forces from your imagination or based on a film or book. An optional background, the Second Sphere, is also included.
Wildfire Overkill
The first expansion to the Wildfire science fiction miniatures skirmish game. Includes a small number of rules clarifications from the main rulebook based on player feedback, followed by a whole host of optional rules to enrich your games. Six army lists are provided.
Xenocide: Firefight
Xenocide: Firefight is an update of the older Xenocide rules. It is a game of sci-fi miniature combat, based on squads of individuals. It will be best played with 15mm or 28mm figures.
Zoid Battle
A hex-based game for the Zoids toys from Tomy/Hasbro, with a simple construction system so you can make up your own zoid's stats and weapons.