CosmicR (./19) :

There's a version of Doom on the ZX Spectrum - uses a 3.5mhz Z80 as its CPU (Basically a slower version of the Neo Geo's sound processor)...

I can say even more - there is a version of Doom for the Commodore VIC-20 (proof is in this video since 18:06 moment).

However I think the Neo Geo's greatest asset is its huge cart capacity so maybe pre-rotated wall blocks and floor pieces...

Pre-rotated? Wait a minute, does Neo-Geo really can`t to rotate sprites at real time?