dark city (https://github.com/darken33) maybe he wants to import from sourceforge, ansonsten svn import to github
DOOM engine (https://github.com/id-Software/DOOM)
endgame singularity recursive clone (bei anderen auch)
fosslinux.com
github - dwarfcorp
github.com/Attnam/ivan
gitlab.com/librebob/athenaeum
Hedgewars
heXon
holyspirit/lechemindeladam cvs conversion?
http://directpython.sourceforge.net/
http://icculus.org/airstrike/
http://icculus.org/asciiroth/
http://icculus.org/avp/
http://icculus.org/bitstream/
http://icculus.org/blackshades/
http://icculus.org/d2x/
http://icculus.org/duke3d/
http://icculus.org/freespace2/
http://icculus.org/freyja/
http://icculus.org/hge-unix/ http://hge.relishgames.com/
http://icculus.org/jugglemaster/
http://icculus.org/jumpnbump/
http://icculus.org/pyddr/
http://icculus.org/rott/
http://icculus.org/tennix/
http://icculus.org/toby/
http://libsdl-android.sourceforge.net/
http://linball.sourceforge.net/
http://psyco.sourceforge.net/
http://pyopengl.sourceforge.net/
http://retrospec.sgn.net
http://sam.zoy.org/monsterz/
http://vamos.sourceforge.net/
http://www.fifengine.net/
http://www.moddb.com/mods/goldeneye-source
http://www.newbreedsoftware.com/s
http://www.plasmapong.com/plasma-pong/plasma-pong/
http://www.zsnes.com/ emulator/platform
https://appimage.org/
https://blends.debian.org/games/tasks/
https://cocainediesel.fun/
https://duion.com/games/uebergame/main
https://empiredirectory.net/
https://empiredirectory.net/index.php/downloads/viewdownload/6-server-software/13-empire-server
https://en.wikipedia.org/w/index.php?title=Etterna_(Game)&action=edit&redlink=1
https://en.wikipedia.org/w/index.php?title=GNU_Backgammon&action=edit&redlink=1
https://en.wikipedia.org/w/index.php?title=Golden_Age_of_Civilizations&action=edit&redlink=1
https://en.wikipedia.org/w/index.php?title=Kdegames&action=edit&redlink=1
https://en.wikipedia.org/w/index.php?title=Minetest&action=edit&redlink=1
https://en.wikipedia.org/w/index.php?title=Simon_Tatham%27s_Portable_Puzzle_Collection&action=edit&redlink=1
https://en.wikipedia.org/w/index.php?title=Simple_Solitaire_Collection&action=edit&redlink=1
https://en.wikipedia.org/w/index.php?title=Super_Tux_Party&action=edit&redlink=1
https://en.wikipedia.org/w/index.php?title=Trigger_Rally&action=edit&redlink=1
https://en.wikipedia.org/wiki/Abuse_(video_game)
https://en.wikipedia.org/wiki/Arx_Fatalis
https://en.wikipedia.org/wiki/AssaultCube prop. content
https://en.wikipedia.org/wiki/Crystal_Space
https://en.wikipedia.org/wiki/GNOME_Games_Collection
https://en.wikipedia.org/wiki/GNU_Chess
https://en.wikipedia.org/wiki/GNU_Go
https://en.wikipedia.org/wiki/List_of_commercial_video_games_with_available_source_code
https://en.wikipedia.org/wiki/MUD#Spread
https://en.wikipedia.org/wiki/MUD_client
https://en.wikipedia.org/wiki/No_Gravity_(video_game)
https://en.wikipedia.org/wiki/One_Hour_One_Life
https://en.wikipedia.org/wiki/Passage_(video_game)
https://en.wikipedia.org/wiki/Rigs_of_Rods
https://en.wikipedia.org/wiki/Rocks%27n%27Diamonds
https://en.wikipedia.org/wiki/Scorched_3D
https://en.wikipedia.org/wiki/Seven_Kingdoms_(video_game)
https://en.wikipedia.org/wiki/Sopwith_(video_game)
https://en.wikipedia.org/wiki/StepMania
https://en.wikipedia.org/wiki/SuperTux
https://en.wikipedia.org/wiki/Teeworlds
https://en.wikipedia.org/wiki/Ten%C3%A9s_Empanadas_Graciela
https://en.wikipedia.org/wiki/Tux,_of_Math_Command
https://en.wikipedia.org/wiki/Warmux
https://fedoraproject.org/wiki/SIGs/Games#List_of_games_we_will_NOT_package
https://flathub.org/home (use it for Linux packaging) / https://flathub.org/apps/category/Game
https://freegamer.blogspot.com/2015/11/top-3-open-source-pinball-games.html
https://futurepinball.com/
https://github.com/a-nikolaev/curseofwar
https://github.com/afritz1/OpenTESArena
https://github.com/ajweeks/FlexEngine
https://github.com/amerkoleci/alimer
https://github.com/amerkoleci/vortice
https://github.com/AmrikSadhra/OpenNFS
https://github.com/amroibrahim/DIYDoom
https://github.com/angband/angband
https://github.com/Anthonymcqueen21/Pygame---Alien-Invasion
https://github.com/ao-libre/ao-cliente
https://github.com/apsillers/lords-of-the-fey
https://github.com/apsillers/Taggem
https://github.com/arianne/stendhal
https://github.com/ArmageddonGames/ZeldaClassic
https://github.com/AxioDL/urde
https://github.com/b3dgs/lionengine
https://github.com/b3dgs/warcraft-remake
https://github.com/bitcraft/PyTMX
https://github.com/bvschaik/julius
https://github.com/ByoxCode/DrawView
https://github.com/Calinou/libre-pinball
https://github.com/Chluverman/android-gltron
https://github.com/Chris3606/GoRogue
https://github.com/ChrisDill/Raylib-cs
https://github.com/codepath/android_snake_game
https://github.com/collections/game-engines (only OS)
https://github.com/collections/javascript-game-engines (only OS)
https://github.com/collections/pixel-art-tools (tools)
https://github.com/collections/productivity-tools (maybe for statistical purposes)
https://github.com/collections/software-development-tools (maybe we can apply some of them across the board)
https://github.com/collections/tools-for-open-source (maybe we can apply some)
https://github.com/collections/web-games (only OS)
https://github.com/CompletelyFairGames/dwarfcorp
https://github.com/Cortrah/SpaceOperaDesign, https://github.com/Cortrah/SpaceOperaRuby/blob/master/design/turnstyles.md
https://github.com/cubei/FlappyCow
https://github.com/cxong/cdogs-sdl
https://github.com/cyberegoorg/cetech
https://github.com/DaemonEngine/Daemon
https://github.com/Dariasteam/TowerJumper
https://github.com/demonixis/C3DE
https://github.com/discosultan/penumbra
https://github.com/eprikazchikov/thunder
https://github.com/ErikLetson/torso-ninja
https://github.com/ErikLetson/torso-ninja-2
https://github.com/Ershany/Arcane-Engine
https://github.com/Esenthel/EsenthelEngine
https://github.com/estevaofon/angry-birds-python
https://github.com/etternagame/etterna
https://github.com/falltergeist/falltergeist
https://github.com/francot514/FreeSims
https://github.com/freeboardgame/FreeBoardGame.org
https://github.com/FreeCol/freecol
https://github.com/FreezingMoon/AncientBeast
https://github.com/gamearians
https://github.com/GentenStudios/quartz-engine
https://github.com/GlPortal/glPortal
https://github.com/GunshipPenguin/open_flood
https://github.com/hedgewars/hw
https://github.com/hparcells/cards-against-humanity
https://github.com/Interkarma/daggerfall-unity
https://github.com/Interrupt/delverengine
https://github.com/jcarolus/android-chess
https://github.com/juzzlin/DustRacing2D
https://github.com/lexica/lexica
https://github.com/libretro/libretro-prboom
https://github.com/MadDeCoDeR/Classic-RBDOOM-3-BFG
https://github.com/magefree/mage
https://github.com/MaKiPL/OpenVIII
https://github.com/marukrap/ProceduralMapGenerator
https://github.com/miki151/keeperrl
https://github.com/MovingBlocks/DestinationSol
https://github.com/nicolodavis/boardgame.io
https://github.com/notapixelstudio/superstarfighter
https://github.com/Novum/vkQuake
https://github.com/NYRDS/remixed-dungeon
https://github.com/OpenBricks/openbricks
https://github.com/OpenDungeons/OpenDungeons
https://github.com/openitg/openitg
https://github.com/OpenMandrivaAssociation
https://github.com/openMSX/openMSX
https://github.com/opensourcedesign
https://github.com/opentomb/OpenTomb
https://github.com/OpMonTeam/OpMon
https://github.com/OSSGames
https://github.com/OSSGames/GAME-SDL-ACTION-Blobwars_Metal_Blob_Solid
https://github.com/PanosK92/SpartanEngine
https://github.com/pelya/commandergenius
https://github.com/pld-linux
https://github.com/ptitSeb/gl4es
https://github.com/raysan5/rfxgen
https://github.com/REGoth-project/REGoth-bs
https://github.com/residualvm/residualvm
https://github.com/romlok/godot-gdhexgrid
https://github.com/RonenNess/GeonBit.UI
https://github.com/rpgboss/rpgboss
https://github.com/rwengine/openrw
https://github.com/saniv/free-game-art/blob/master/foss-copyright-infringement-records.md
https://github.com/search?p=1&q=sunrider&type=Repositories, sunrider
https://github.com/sirjuddington/SLADE
https://github.com/smcameron/space-nerds-in-space
https://github.com/SneakyTactician/MagicalLife
https://github.com/sourcehold/Sourcehold
https://github.com/sphair/ClanLib
https://github.com/sromku/memory-game
https://github.com/stephenjsweeney/blobwarsAttrition
https://github.com/STJr/SRB2
https://github.com/suijingfeng/vkOpenArena
https://github.com/SuperTux/supertux
https://github.com/taisei-project/taisei
https://github.com/team-eternity/eternity
https://github.com/The-Powder-Toy/The-Powder-Toy
https://github.com/theaigames
https://github.com/TheAssemblyArmada/Chronoshift
https://github.com/TheAssemblyArmada/Thyme
https://github.com/tonihele/OpenKeeper
https://github.com/tpcstld/2048
https://github.com/unknown-horizons/godot-port
https://github.com/ValyriaTear/ValyriaTear
https://github.com/vilbeyli/VQEngine
https://github.com/Vocaluxe/Vocaluxe
https://github.com/Wargus/stratagus
https://github.com/wesnoth/haldric
https://github.com/xLAva/JediOutcastLinux
https://github.com/XProger/OpenLara
https://github.com/xyzz/openmw-android
https://github.com/yairm210/UnCiv
https://github.com/yiotro/Antiyoy
https://gitlab.com/LibreGames
https://keeperrl.com/
https://lgdb.org/game/wolfpack-empire
https://libregamewiki.org/Libregamewiki:Suggested_games#Likely_sources_for_more_free_games
https://neverball.org/
https://nukeykt.retrohost.net/
https://openage.sft.mx/
https://osdn.net/softwaremap/trove_list.php?form_cat=80
https://packages.debian.org/sid/games/etw
https://play.google.com/store/apps/dev?id=8387589286898375037 (where is the source, not open source otherwise)
https://pypi.org/project/CherryPy/
https://pypi.org/project/neteria/
https://pypi.org/project/networkx/
https://pypi.org/project/PyAMF/
https://pypi.org/project/simplejson/
https://pypi.org/project/SQLAlchemy/
https://pypi.org/project/TurboGears/
https://revolutionarygamesstudio.com/ Trhive
https://salsa.debian.org/games-team/etw
https://secretchronicles.org/en/
https://sourceforge.net/projects/actiongame/
https://sourceforge.net/projects/deng/
https://sourceforge.net/projects/ettu/
https://sourceforge.net/projects/hhexen/
https://sourceforge.net/projects/librecardgame/
https://sourceforge.net/projects/mininghaze/ - download didn't work
https://sourceforge.net/projects/pinball/
https://sourceforge.net/projects/pixellight/
https://sourceforge.net/projects/realmforge/
https://sourceforge.net/projects/uhexen2/
https://sourceforge.net/projects/vpinball/
https://sourceforge.net/projects/webchess/
https://sourceforge.net/projects/zaz/
https://stabyourself.net/ (all projects there)
https://web.archive.org/web/20150526225753/http://sourceforge.net/projects/mameosx/
https://web.archive.org/web/20150527150705/http://sourceforge.net/p/forge/community-docs/SourceForge%20Games/ (schon erledigt)
https://wiki.debian.org/Games/Unsuitable
https://www.b3dgs.com/v7/page.php?lang=en&section=projects
https://www.bsframework.io/
https://www.fandom.com/topics/games (look for media links, example https://creatures.fandom.com/wiki/Openc2e)
https://www.fosshub.com/about.html
https://www.openhub.net/ (search for games)
https://www.piston.rs/
https://www.reddit.com/r/opensource/comments/cs6m3y/a_list_of_fossrelated_projects_people_to_follow/
https://www.reddit.com/r/opensourcegames/
https://www.reddit.com/r/opensourcegames/comments/celw6c/top_3_open_source_pinball_games_2015/
https://www.renpy.org/ (also all projects linked there)
https://zope.readthedocs.io/en/latest/
lionengine github
nexuiz - https://github.com/atphalix/nexuiz
nexuiz - https://github.com/OpenMandrivaAssociation/nexuiz/blob/master/nexuiz.spec
nexuiz - https://github.com/pld-linux/nexuiz/blob/master/nexuiz.spec
nexuiz - https://github.com/smlinux/nexuiz
nexuiz - https://gitlab.com/nyov/nyovs-nexuiz
nexuiz - https://gitlab.com/xonlegacy/xonlegacy
pyglet
Quatter
query alternativeto with only open source...
scrape moddb?
TrueCraft
wxPython