A live link: http://users.ece.cmu.edu/~ganger/712.fall02/papers/p761-thom...

Quake 3 was still completely C, IIRC. You might be thinking of Doom 3?

the rerelease mentioned here rename .c to .cpp globally but the code base is still c, why is that? I thought it was rewritten in c++.

It's a light touch (looks like the original structure is mostly intact) but if you search for 'std::' in, say, https://github.com/id-Software/quake2-rerelease-dll/blob/mai... you'll see there's some C++ stuff floating about.

I quite enjoyed The Battle of Polytopia -- it's a very cut down Civ style game.

Warhammer 40,000: Gladius - Relics of War is enjoyable too -- it's quite simplified (the space marines can only build the one city, as appropriate for a 40k game there's zero diplomacy, etc).

Warlock - Master of the Arcane is a Master of Magic spiritual successor, and I found it a lot less taxing than Civilization in the late game.

The point of Crispy is to be closer to vanilla than ports like GZDoom, Zandronum, PRBoom, etc, but still remove some static limits (that custom maps need to work) and increase the render resolution (which GZDoom etc do, but vanilla and ports like Chocolate Doom don't).

Basically it's Chocolate Doom (which is essentially 1994 Doom, but it builds and runs on modern systems), but a little more easy to use and a little more compatible.