Tomb Raider 1.
I'm replaying the remastered trilogy for the first time since I was a teenager. The level design is outstanding. Very clever re-use of the same areas, just at different heights.
It's inspiration from side-scroller prince of persia (also played this obsessively as a young child) is palpable. The movement system is revolutionary.
And the enemy progression is hilarious. First you fight some bats, then you fight some wolves, then you fight motherfucking Velociraptors, then a goddamned T-Rex. And thats not even close to the weirdest enemy you'll fight. Boss battles are evenly spaced until they aren't. when you have two boss battles immediately one after the other.
And then eventiually, you get to the pulsating flesh caves...