Hi, I've tried to play it by using the mouse and keyboard.
The First Problem: It is impossible to bind any controls via the menu, or even a config, apparently. Meaning that I have to use the arrow keys on my laptop, as my main keyboard does not have them (yeah, yeah), this is pretty awkward.

The Second Problem: The graphics in-game do not seem to acknowledge that I'm using keyboard and mouse, so they show me the gamepad graphics.

These problems combine, into, The Third Problem: When it came time to tell me how to use the controls for "situational awareness", it told me to use the right analog stick. I tried the mouse (mouse grab failed when it was windowed, by the way), I tried WASD, neither worked.

I remember playing this via the demo several years(?) back, and I had a lot of fun, now I am not even sure how I am supposed to play it.

Thanks for reading, and for making what I remember to be a pretty fun game!

(responded already to your email, just posting here in case it would help anyone else)

You can rebind controls in the "Options" -> "Rebind Controls" menu.

The game should recognize that you want to use the mouse if you simply click anywhere in the window. I tend to right-click because a left click will fire your current weapon.

If you have a gamepad plugged in that you don't want to use, or some kind of USB device which could be construed as a gamepad, I suggest you either unplug it or make sure it's in some kind of state where it's not going to provide any input. If any input occurs, the game assumes you want to use the gamepad.

Thank you for this, I managed to remove the gamepad in the rebind controls menu (I think I tried to click on it, and that specific menu was only accessible via the arrow keys, or vice versa. the menu systems are kind of inconsistent and each menu seems to prefer something different).
However despite not having a gamepad set, the game continued to use gamepad graphics for the tutorial, luckily I had tried it (and it ran perfectly fine) on windows first, so I knew the controls.