: I was really only thinking the gameplay, not the hardware demands (the speed
: the character runs, regenerating health and bulky, accurate enemies that
: forces most of the game to be bottlenecked with repeatedly ducking behind
: cover, Duke Nukem losing his breath after 10 seconds of jogging but being
: able to sit around and do benchpresses however long he likes (and make it
: frustrating for the player to complete a benchpress to boot), etc.).
: And then there's the unskippable cutscenes and handholding tutorials.
Ugh, tutorials. I still am of the opinion that you should just toss the character into the game and have 'em figure it out (well, within reason. Don't go mapping "forward" to "F6" without telling anyone). You can respawn, and do it again until you've got it figured out (unless you're smart and realise that yellow blood coming out of BoBs isn't normal). In Marathon, it's even canon (see Infinity's timeline).
And as for cutscenes, I will never stop loving terminals. They do away with having annoying 'helpers' (if you don't want to read the thing, just spam tab) and somehow manage to make the story not feel one-sided, despite the fact that YOU NEVER TALK. And there's just something awesome about a future in which AI's communicate with phosphorous-green text on a computer terminal (rather than as an almost-expressive female voice in a smartphone). I look at the AIs of Marathon as a small bit of optimism in the sea of "backstabbing politics", starving Martians, and slave empires. (I guess it says a lot about your world if its brightest aspect is talking to insane computers).
And regenerating health almost never makes sense in games, unless it's like in, say, PiD where you gain health by resting.
All that said, there ARE annoyingly slow places in Marathon. Colony Ship For Sale, Cheap. Enough said.