Hm, the stick must be triggering button #2. I think the internal joystick settings may not be set up correctly for the CPC. I have an ArcadeR stick too so I know it works, but I had to swap the ribbon cable on the inside of the stick from one connector to the other before I could use it as a 2 button CPC controller. IIRC it comes from the factory in C64 configuration.
Sorry, it would really need a full rewrite to run on the GX. It is very dependent on having 128k and a disk drive to work. And the GX deserves its own enhanced version really!
Looks like it just needs a small adjustment to the frame. If using the RVM emulator you might also need to adjust the overscan settings too, I noticed. It's because the game goes all the way to the bottom of the screen, and some emulators may clip this off, depending on how the screen settings are. You should be able to adjust this. Also it should look fine on a real monitor.
That's when it's loading and/or saving to disk. I don't know if the Mister core provides direct file access as well as disk drive emulation, but if you can run it directly from a directory rather than as a disk image you might be able to get it to load a lot faster. I don't know anything about the Mister, but running from an M4 card into a real CPC, the loading times are almost zero, so maybe you can set up the Mister to behave similarly.
