GZDoom: https://steamdb.info/tech/Engine/GZDoom/
Godot: https://steamdb.info/tech/Engine/Godot/
Love: https://steamdb.info/tech/Engine/Love2D/
FNA: https://steamdb.info/tech/Engine/FNA/
- Godot: https://godotengine.org/showcase/
- Löve (doesn't have a separate page, but showcases a few games at the bottom of the page): https://love2d.org
- DragonRuby: https://dragonruby.org/toolkit/game/samples
- Haxe (though not an engine per se): https://haxe.org/use-cases/games/
Papers Please and Dead Cells were made using Haxe with OpenFL as the framework (not completely sure).
These are only the games I've played that are built on FOSS engines. I'm sure there are many more.
https://torque3d.org was used on Airship Dragoon, Marble Blast Gold, Penny Arcade Adventures, Legions: Overdrive and descends from the original Tribes engine.
Hellbreaker, Bit Champs with https://u3d.io
And plenty of successful games with Ogre, including Torchlight: https://www.ogre3d.org/showcase
[1]: https://libgdx.com/
It’s not perfect because some engines (like Godot) have export options to bundle games into a single executable that SteamDB can’t use for engine detection.
If you are wondering what modern open source engine to use, Godot seems to be it. If you are wondering if any FOSS engines ship games, the answer is an overwhelming yes. If you are wondering how to write an engine, any of these OSS engines will teach you what you need to know (or at least get you going).
https://github.com/ConfettiFX/The-Forge was used in No Man's Sky, Hades and Starfield.
https://github.com/jrouwe/JoltPhysics is the physics engine in Horizon Forbidden West.