Out of curiosity, how much slower is this than an actual CPU?
For a similar case, check Eforth+Subleq. If this guy can emulate subleq CPU under a GPU (something like 5 lines under C for the implementation, the rest it's C headers and the file opening function), it can run Eforth and maybe Sokoban.
It might be worth having a CPU that's 100 times slower (25 MHz) if 1000 of them could be run simultaneously to potentially reach a 10 times speedup for embarrassingly parallel computation. But starting from a hole that's 625000x slower seems unlikely to lead to practical applications. Still a cool project though!