Now that I see this, I'd curious if something like Nethack 3.4.3 or Slashem could be rewritten in T3X0 and be playable under 286 machines:
There's a working Rogue port for Minix2 under a 16 bit CPU (and for the Z Machine too, and GBA, and several others...), but I think even Hack 1.0.3 would be too big to fit under a 286 with 640k.
It would be a good start if Nethack 1.3d got working under CP/M for instance, rewritten with T3X0 and some ASM hacks for speeds...