I redownloaded the game and the OPK issue was finally resolved.
The game works like a charm. Thanks for making a GCW0 port!
There are two issues at the moment that I have noticed:
1) The game is downscaled from 640x480, which makes some of the text and gui elements unreadable.
2) The input mapping is not well adapted for GCW0 (ie. car acceleration/break is done with D-PAD UP/DOWN, while I think having it mapped to A/B would work much better).
Although I understand this game is still in development, so these issues will hopefully be fixed in the future