There's a portion in the game when your brother Paul is sick and he tells you to leave him to fight off enemy goons alone. Apparently you can fight your way through the hotel and he survives all the way to the end of the game!
When the sequel came out, I was like "why the fuck is Paul still alive"
The issue with this is that the game doesn't really communicate this fact to you, and not killing the goons technically should mean that they're still going to go upstairs at some point and kill Paul.
The most hilarious part of this is that Paul himself says he's too weak to climb through the window, but as soon as those goons bust in through the front door, he whips out a 50 lb flame thrower and starts strafing around at 30 mph like he's in the motherfucking murder olympics.
You can kill Anna on the plane where you're supposed to kill Lebedev; the game accounts for this with voice dialogue and everything. Crazy. At that point in the game there is no reason for you to even try (and she's a tough match) unlike later on --- but you can!
I tried playing Alice a couple times when I got Steam in 2023, and I couldn't get into it. Tried another game from that era: Made it about halfway through Half Life 1 on a long flight and couldn't get into it either, even after I'd played Alyx.
It's wild how games that were considered state-of-the-art when we were kids can feel unplayably unpolished today.
IIRC Quake used “a” and “d” to… turn, instead of strafe, by default. Absolute madness. Can be played without a mouse I think(?).
On the other hand, it is still very cool that you can get the bad guys to fight each other sometimes. That should be a feature in every game really.