I know I'm a million years late, but I’m finally trying the Halo Master Chief Collection. I like that you can switch between oldschool and remake graphics, but honestly at this point I think I agree that the remake needs a remake — it looks really dated. Sounds like that's exactly what's in the works though with their fancy new Unreal Engine project, so let's see.

In the meantime, I'm refamiliarizing myself with Halo CE, which I last played through on a Titanium PowerBook in 2003

While the original Halo might feel mechanically dated in many ways, it's remarkable just how similar its template is to modern games. It's clear the genre as it exists today owes far more to Halo than it does to DOOM, and that's why it's held right up there
I'd also forgotten just how dramatic a shift Halo takes halfway through, when it turns into a horror game and switches up the enemy types completely. Later games lost that element
@stroughtonsmith I’ve never played Halo but I wonder if that’s where Half-Life 2 got the idea for the Ravenholm sequence.