Congestion: 64 is a joke megawad which draws inspiration from the similar megawad Congestion 1024. It follows the same premise as Congestion 1024, namely that all levels fit within a small area. However, while Congestion: 1024 restricted mappers to a small but workable 1024x1024 unit area, all levels in Congestion: 64 are contained within a dramatically limiting 64x64 area. As a comparison, the player in Doom is 32x32 units in size. Unlike Congestion: 1024, which was a community project, all Congestion: 64 levels were created by a single mapper named "1337 Doomer".
Although a joke WAD, the levels show creativity in the use of the restricted space. While the first few levels contain only a small 64x64 room with an exit switch, later levels use many of the different features of the Doom engine, including elevators, keycard-protected doors, rising stairs, moving floors and even a teleporter. In one level, the correct elevator must be selected to retrieve the keycard for the exit door; selecting the wrong elevator causes a barrel to be detonated, killing the player.
Many players appear to have been confused by MAP14, where the exit switch is located behind a door that opens five minutes after the level start. The only way to complete this level is to wait five minutes until the door opens. This lead several players to question whether there was a bug in the level.
Some of the levels appear to follow the original Doom 2 levels: for example, in MAP06 ("The Crusher"), the player must press the exit switch before being crushed by a crushing ceiling. MAP23 ("Barrels of Fun") finds the player in a room with three barrels, while the Wolfenstein levels (MAP31 and MAP32) follow a Wolfenstein theme.
The megawad was released several days after Congestion: 1024, and as a result the two appeared together in the newstuff review.