Collect a data disk and read its content.

Don't leave your outpost for 15 minutes.

Finish off episode 1's boss with the chainsaw.

End a level with no armor and a single health point left.

Start the game for the first time.

Kill an enemy with a grenade that bounced off a wall.

Kill a flayer spawn with a melee attack.

Kill the monster!... you know, that one? With the thing that does the stuff?