Kill a CyberDemon with your fists in singleplayer.
Kill 20 enemies while in berserker mode on a single map in singleplayer.
Kill 20 enemies with your chainsaw on a single map in singleplayer.
Complete the DOOM 2: No Rest for the Living single player campaign on "I'm Too Young to Die!" or higher.
Complete the DOOM 2: Master Levels single player campaign on "I'm Too Young to Die!" or higher.
Complete the Final DOOM: Plutonia Experiment single player campaign on "I'm Too Young to Die!" or higher.
Complete the Final DOOM: TNT Evilution single player campaign on "I'm Too Young to Die!" or higher.
Complete the DOOM 2: Hell on Earth single player campaign on "I'm Too Young to Die!" or higher.
Complete the Ultimate DOOM single player campaign on "I'm Too Young to Die!" or higher.
Find a BFG in singleplayer.
Complete a Level with 100% Kills, Items and Secrets in singleplayer.
Complete any Level in any difficulty in singleplayer.
Find a Secret in any Level in singleplayer.