[HeavyStorm]

Yes, C. Like all id games up to... Doom 3, if I'm not mistaken? Only then they switched to C++. There's absolutely nothing impressive about this fact.

[brokencode]

Nobody claimed it was impressive. It’s a little unusual to use C instead of C++, but that’s about it.

[direwolf20]

It's impressive these days when software quality and craftsmanship is declining.