OptiDoom, a 3DO port/enhancement of Doom based on the original released source code

Optimus6128 aka Bugo The Cat writes:

"The primary focus of this port is to try and change the rendering engine in the hopes of improving the very slow performance on 3DO, an uphill battle so far."

http://bugothecat.net/releases/3DO/optidoom/optidoom_main.html