The Amiga home computer platform was fairly popular during the late 1980s and 90s, but it was widely considered that it was not possible to do a game like Doom on this platform due to technical restrictions of the standard Amiga graphic chipset, which was built to do scrolling sprite based games, not pixel-based rendering.
Quickly after the release of the source code, several people jumped on the bandwagon and ported Doom to the Amiga. This resulted in several different ports which competed for the Amiga userbase. Only two ports survived this competition, while the others were abandoned.
The most well-known ports (680x0 Amigas):
There are also a few ports for the Amiga PPC platform:
Running the 680x0 ports of Doom requires at least a Motorola 68030 CPU with about 50 MHz and a few megabytes of extra memory.