Hey everyone.
I've seen several lists around the internet mentioning different resolutions for games but none of the lists seem to mention Nemesis 90 Kai being able to switch to 15kHz.
I figured I would just let people know that I accidentally figured out that you can indeed swap between 15 and 31kHz. For me all I had to do was just press the - key on the right side keypad. I am using a US keyboard with an adapter into the X68k and I don't know if that makes a difference but figured I'd mention it.
Hope this helps!
It's the HELP key on a real keyboard. Quite a few games work this way.