I hate how I spent so much money on the HTC Apache back in the day only so it could become a useless pile. I saw that post up there on a successful PSX game on the Apache and I got really excited.
I tried installing all that same stuff (the D3D driver, the overclocking utility, FPSEce) only as for the Apache's ROM, I used a custom ROM I built with PPCKitchen (it couldn't differ much from the 'clean' ROM, because you can hardly add anything to it because of the limited space).
I tried running Castlevania: Symphony of the Night and it didn't run past the "Press Start" screen. I was hoping that since the game is a fairly simple sidescroller, it would run on the Apache, but no luck.
So far (for me) the only emulator I've tried that runs well and plays smooth on the Apache is that PocketNester. The PocketSNES runs about like the DreamSNES for Dreamcast: only runs at an acceptable framerate without sound. I thought it would be better, since the Dreamcast runs at 200mhz and the Apache can be overclocked to 624mhz... Granted I've only tried these three emulators, but those were the three I knew I'd probably get the most use out of.
With this in mind, I figure a gameboy emulator would run perfectly also.