From DoomWiki.org

CellDoom is a source port of the original Doom engine to the Smartphone 2002 release of Windows CE by "Z-Infinity", however it will run on any subsequent release of Windows CE for Smartphones (currently branded as Windows Mobile Standard). The game runs at a high framerate on even the first Windows CE smartphone device, the HTC Canary (aka Orange SPV), however the unsigned software lock will need to be removed in order for it to run.

The latest release is version 1.6, downloadable via Softpedia (archived 🏛) made in 2006, however the port dates back to at least 2003.