Ways to play Doom64 outside of an actual N64 or emulation has been pretty scarce up until now, and it's a huge shame.
There was a slow trickle starting with SVKaiser's Absolution TC, and Doom 64 EX, but we actually have choices now:
Experiment at your discretion. They're all fun. Most of them rely on the Nightdive Doom64.wad from GOG or Steam, some are still fine with doing a tc of Doom II.
Doom 64 EX + by ATSB.
Doom 64 Super EX Plus by styd051 (for custom monster and extended map support)
Doom CE by molecicco. A modernized approach to both PSX and Doom 64. There's even a bizarre add-on mod that combines them.
Doom 64: Retribution by Nevander
Brutal Doom 64 by Sgt Mark IV
