Writing DOOM in assembler sounds like a...gargantuan task. Is it a case where you can compare assembler output from the original or a start-from-scratch sort of thing?
Probably mostly a start from scratch. Even if you felt like disassembling and trying to grok the PC executable, it wouldn't be especially helpful - the SNES' 65816 CPU (and its SPC700 APU, and the Doom cart's Super FX coprocessor) are completely different than an x86; especially for a performance-intensive game like Doom, you'd likely need to rearchitecture the whole thing.
