Cheat Codes (Doom Eternal)

Cheat Codes, also known as Floppy Disks or simply codes or disks, are collectables in Doom Eternal. They can be collected in missions. Then, when using Mission Select, they can be activated to make tasks less time-consuming for the player. For example, in the mission Taras Nabad, one of the challenges is to get three different glory kills on Pain Elementals. When using Mission Select, the player can activate the Instant Stagger cheat, which makes all non-boss enemies stagger upon one hit.

Trivia
IDDQD and IDKFA are both references to cheats from the original DOOM (1993)

Upon collecting all of the Cheat Codes, the old-timey PC in the Fortress of Doom can be used to play DOOM (1993).