Game/Halo
Halo CE & Legend of Alon D'ar Source Trees
There are some more fleshed out things on the way, slowly but surely, but until then we’ve recently made some more source tree reproductions available for those that like seeing that sort of thing (probably just me.)
This time we’ve got Halo: Combat Evolved, specifically generated from a pre-release build found here, and Legend of Alon D’ar, which was produced from symbols included in the retail US release (oops).
As you can probably see, and might have known already, much of the original Halo was written in C.
As for The Legend of Alon D’ar, it seems much of that was written in C++. The latter is referred to as FireFly, which was apparently an early working title (at least according to MobyGames, which provides no citation, because of course). Another working title was Eternal Blade.
Enjoy!