Alien Swarm, the version of the original redone in the Source engine from Valve has since been released on Steam. While it was awesome as an isometric shooter, thanks to a console command it can be played as an FPS, which is just terrifying.
Complicated as it may seem, if you’ve been playing video games on the PC for an extended period of time, this shouldn’t pose any sort of problem to you. But thankfully, the commands to take you from a sky view and into the boots of your marine have been made available.
In a running game of Alien Swarm simply go to Options > Keyboard > Enable developer console. Then hit ` (to the left of 1) and type:
And then you can experience the terror first hand.