These are the FLOSS games that stand out, list your own favourites or most-play games.
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I would rate all of these, as worth a try:
Shattered Pixel Dungeon
Cube2:Sauerbraten
SGT-Puzzles
Andor's Trail
AssaultCube
Minetest
Neverball/Neverputt
PowderToy
0ad
Fillets-ng
Anuto TD
Xmoto/Bloboats
Flightgear
Kobo Deluxe
Enigma (oxyd)
LiquidWar5
H-Craft Championship
Numpty Physics
Wesnoth
The Dark mod
Have completed SuperTuxKart, BlobWars 1&2, Flare, Frozen Bubble, Hex-a-Hop, Holotz's Castle, SearchAndRescue II, Alex the Alligator, Project:Starfighter, Stormbaan Coureur, Trigger, all are fun.
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Can find details about most of the above games here:
https://libregamewiki.org/List_of_games
FLOSS gaming is excellent, thanks to all these devs and asset creators.
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BONUS TOMT:
I'm looking for the name of a FLOSS Quake1-mod, puzzle game, that was about placing gravity points, to curve a stream of particles around the level, and eventually into the goal target. (May have used irrlicht)
If anyone knows the name of this one, please let me know, it is my white-whale of games.
The Ur-Quan Masters
Formerly known as Star Control 2, and now officially known as "Free Stars: The Ur-Quan Masters" (available for free on Steam).
The game was released open source in the early 2000s when the code from the 3DO port was found.
Since then, there have been plenty of mods, including a demo of a fan sequel, and two full graphics overhauls giving the game HD graphics. Plus optional remixed music.
My favourite mod is UQM Mega Mod, which is probably the most feature-rich mod, and super customizable. You can go for full fan-made HD graphics and music, or switch things over to the vanilla PC experience from 1992. Or you can toggle QoL features or bonuses for added lore if you so choose.
Yes!
I played Ur-Quan way back, and it is a great space battler.
Haven't tried any of the mods yet. Those are some handy recommendations, thanks!