Free open source games

[MrFlibble]

As I get more and more interested in open source software I decided to make a list of games that are both free and open source. These two terms are often treated as synonyms, although there are quite a few commercial games that have been open sourced, and plnety closed-source free games.

The list turned out to be very big, and is by no means complete. I have also included several (very well-known) Apogee model shareware open source games, all of which are explicitly marked as such.

Action
Battle Tanks
BattleCity
Bitfighter
Chickens 2
Chopper Commando
Hyperoid
Gang Garrison 2
GLtron
Knights
Knockin
Liero
Neverball
NiL
OpenLieroX
Savage Wheels
Steel Storm: Episode I [shareware]
Teeworlds
Violetland

Adventure
Adventure Game Studio [engine/SDK]
Beyond the Titanic
Beneath a Steel Sky
Flight of the Amazon Queen
Lure of the Temptress
Drascula: The Vampire Strikes Back
Soltys
Mines
Quest [engine/SDK]
SLUDGE [engine/SDK] [SourceForge]
Supernova

Arcade
Frozen Bubble
Hex Bubbles
LBreakout2
Multiplex
Open Hexagon
Paku Paku
Rocks'n'Diamonds
Snarf
Zorx

Artillery
Atomic Tanks
Hedgewars
N.A.T.O.W.
Scorched 3D
Scorched Earth 2000
WarMUX
xscorch

Beat 'Em Up
Open Mortal

Board
GNU Backgammon
JavaRisk
Ludus Regius
NetRisk
OGS Mahjong
OpenFracas
Pioneers
Scrabble 3D
yura.net Domination

Card
PokerTH
PySol
PySolFC
XM Solitaire

Chess
ChessV
DreamChess
GNU Chess
PyChess
The Genius
XBoard/WinBoard

First-Person Shooter
CodeRED - Battle for Earth [download]
CodeRED - The Martian Chronicles [download]
Crystal Core [Crystal Space 3D engine tech demo]
Cube [engine/SDK]
Cube 2: Sauerbraten
Descent [shareware]
Doom [shareware]
Duke Nukem 3D [shareware]
Freedoom
Heretic [shareware]
Ken's Labyrinth
Marathon Trilogy
Open Quartz
OpenQuartz 2
OQPlus
Quake [shareware]
Retribution [engine/SDK]
Rise of the Triad [shareware]
Shadow Warrior [shareware] [Steam free version]
Wolfenstein 3-D [shareware]

Multiplayer/Arena FPS
Alien Arena
Arena of Honour
Assault Cube
Assault Cube Reloaded
BZFlag
DDay: Normandy [development website]
Digital Paint: Paintball 2
fight win prevail [development suspended]
Nexuiz Classic
OpenArena
Red Eclipse
Smokin' Guns
Tremulous
Unvanquished
Warsow
Wolfenstein: Enemy Territory
World of Padman
Xonotic
Zero Ballistics

Misc
BillardGL
Frets on Fire
StepMania
UltraStar
Word Whiz

Platform
Abuse
Dave Gnukem [download]
Jump 'n Bump
Jumpman Lives!
Frogatto & Friends
Go Ollie!
Mario clone
Prince of Persia
Secret Maryo Chronicles
Smash Battle
SuperTux
Xargon
Yo Frankie!

Puzzle
DroidQuest
Enigma
Kentris
Kroz
Numpty Physics
Pingus
SDL Scavenger
Small Tetris
Sokoban
Tile World
Tiny Tetris
X-Moto

Racing
Armagetron Advanced
Dakar 2011
Dolphinity Racer
MiniRacer
Speed Dreams
Stunt Rally
SuperTuxKart
T1 Car Racing Simulation
TORCS
Trigger Rally
Ultimate Stunts
VDrift

Real-Time Strategy
0 A.D.
Aleona's Tales
Bos Wars
Clonk
Clonk 2 Debackel
Clonk 3 Radical
Clonk Planet 4.65
Clonk Endeavour 4.95.5
Clonk Rage
Commander Stalin
Dark Oberon
Glest
Globulation 2
MegaGlest
Open Imperium Galacitca
OpenClonk
OpenDungeons
Seven Kingdoms: Ancient Adversaries
SpringRTS [engine/SDK]
Unknown Horizons
Warzone 2100
Widelands
Zero-K

Role-Playing
Blades of Exile
Erebus
Escape From The Maze
Fall of Imyrin
FLARE [engine/SDK]
FreedroidRPG
GNU FreeDink
Hero of Allacrost
Lips of Suna
LostHero - Story of Gilgamesh
NAEV
RuneSword II [download latest version]
Summoning Wars

Roguelike
Angband
Brogue
Dungeon Crawl Stone Soup
Fame
Linley's Dungeon Crawl
Moria
NetHack
Rogue
S.C.O.U.R.G.E.: Heroes of Lesser Renown
SLASH'EM
Tales of Maj'Eyal

RPG Maker
Advanced RPG Maker [engine/SDK]
EasyRPG [engine/SDK]
Mokoi Gaming [engine/SDK]
Open RPG Maker [engine/SDK]
OpenLegends [engine/SDK]
Solarus [engine/SDK]
Sphere RPG Engine [engine/SDK]

Massively Multiplayer RPG
Eternal Lands
PlaneShift
WorldForge

Sandbox
Manic Digger
Minetest
Terasology

Shoot'Em Up
AstroMenace
Chromium B.S.U.
Kiloblaster
M.A.R.S.
Powermanga
Project: Starfighter
SDL Sopwith
SHMUP - AirWars
Solar Wolf
Tyrian
Vacuum Magic

Simulation
Flight
Combat Simulator Project
decopter [engine/SDK]
FlightGear
Fly! Legacy
Flying Guns [engine/SDK]
GL-117
Palomino
Slope Soaring Simulator
Thunder&Lightning

Managerial
FreeTrain
Lincity
LinCity-NG
Micropolis
OpenCity
OpenTTD
Simutrans
Skyscraper
Spice Trade

Space flight
Flight Commander [source code available upon request]
No Gravity
Oolite
Paragon
Pioneer
Space Combat
Starshatter: The Gathering Storm [source]
Vega Strike

Various vehicles
Danger from the Deep
Rigs of Rods

Sports
Slam Soccer 2006
Yoda Soccer

Third-Person Shooter
Dead Justice

Turn-Based Strategy
Advanced Strategic Command
The Battle for Wesnoth
FreeLords
GEMpire
LordsAWar!
UFO: Alien Invasion
UFO2000

4X
Antiquity
C-evo
Classic Empire
Conquests
Freeciv
FreeCol
FreeOrion
Iron Seed
Kingdoms
Stellar Conquest III
Thousand Parsec

Turn-Based Tactics
Crimson Fields
MegaMek
Open Panzer
OpenGeneral

[MrFlibble]

Added OpenTyrian. The source code in this case was translated from TurboPascal to C but it's still the original code, not a recreation from scratch.

[Lunick]

Added OpenTyrian. The source code in this case was translated from TurboPascal to C but it's still the original code, not a recreation from scratch.

Is TurboPascal and Pascal the same thing?

A month or so ago I asked one of the Halloween Harry/Alien Carnage devs if they could release the source code for said game and they said they didn't have it but the other developer of the game did. He also told me that it would probably be useless since it was coded in Pascal. Hearing that Tyrian was made from a similar coding language, I wonder if it would be that useless

[MrFlibble]

Well, to quote Wikipedia:

Turbo Pascal is a software development system that includes a compiler and an integrated development environment (IDE) for the Pascal programming language running on CP/M, CP/M-86, and DOS, developed by Borland under Philippe Kahn's leadership. From version 6 both a lower-priced Turbo Pascal and more expensive Borland Pascal were produced; Borland Pascal had more libraries and standard library source code. The name Borland Pascal is also used more generically for Borland's dialect of Pascal.

Borland has released three old versions of Turbo Pascal free of charge because of their historical interest: the original Turbo Pascal (now known as 1.0), and versions 3.02 and 5.5 for DOS.

There are tools that facilitate conversion from Pascal to C, such as this one. However as I have only basic knowledge of computer programming I can't help you any further.