For Total Annhialation section: https://zero-k.info/

Zero Knhas been in active dev much longer than BAR, is more mature, has a well-established little cult community, and IMO is the better game. And still OSS ofc.

You really think Skyrim belongs there? I’d agree that Elder Scrolls deserves a place, but what did Skyrim do that wasn’t done by Oblivion or even Morrowind?

Source was not an internal engine, it was an openly available engine used by numerous non-Valve games (The Ship, Garrys Mod, Titanfall, Dear Esther, etc etc).