the game however seems to freeze when gameplay should start...
IIRC its due to the weird ADPCM IRQs not being acknowledged. Its the same for some other ROMs. But it was a long time ago that I've worked on that. BTW: My recordings of the original console tend to make me think that there could be a discrepancy between the weird PCM/ADPCM encoder and the decoder inside the upD1771 chip. Voice samples/effects are really horrendous. A decap might shed a few lights.
