FAQ

Is RigelEngine an emulator?

No, RigelEngine is native code. The original game's assembly code was used as basis to rewrite the game from scratch. The end result is portable C++ code that runs natively on modern operating systems.

RigelEngine does include an emulator for the OPL2 (music chip found on AdLib/Soundblaster cards from the DOS era) in order to play back music and some sound effects, but that's the only part relying on emulation.

Could RigelEngine run Duke Nukem 1 as well?

No, that's not possible. Duke Nukem 1 uses a completely different engine, so it would have to be recreated separately.

There is another (unrelated) project for Duke 1: ReDuke

Could RigelEngine run Cosmo's Cosmic Adventure?

Also no. Cosmo and Duke 2 run on very similar engines, with the latter being an evolution of the former, but there are still many differences. Plus, all the menu code and game logic (player controls, how enemies behave etc.) would have to be reverse-engineered and reimplemented.