Classic Doom for Doom 3 (also known as Classic Doom 3, mod name cdoom) is a Doom 3mod, by Flaming Sheep Software. It recreates the entire Knee-Deep in the Dead shareware episode of Doom. Other episodes are not recreated, partly due to copyright and licensing issues (since the mod is freely distributed, without specific authorisation from id Software), but primarily because the team wished to move over to working on different projects after recreating the first episode.
The mod supports single-player game, as well as deathmatch. When coupled with the Last Man Standing Coop mod, it is also possible to play through the game cooperatively.
Major differences between the original and Classic Doom 3
Features intro and ending cinematic scenes, based and expanded on the original Doom story.
The Doom 1 and Doom 2 automap is not available, nor is the PDA functionality.
Uses Doom 3's GUI surfaces instead of buttons and switches.
No full status messages are shown; As in Doom 3, item names are shown when picked up, and GUI panes have changing text. Some things have sound equivalents; for example, when picking up the chainsaw, you hear "Find some meat!"
Different, but reasonably equivalent, enemies are used. For example, instead of Troopers, Z-Secs are used.
Enemy placement and appearance numbers are slightly different due to the different game balance.
Lots of extra objects, furniture, lighting, wall decorations etc. are used to spice up the levels.
A high-quality recorded soundtrack instead of MIDI.