Thanks for looking into this! For now I resorted to my MEGA65, there it runs without issues. Really nice little game!
Glad to hear that you can play it at least. I have googled a bit and this may be connected to the true drive emulation in The64 (Vice). This thread describes how it was solved for someone (though for other games), but it seems to be a bit fiddly and I have no possibility to verify it unfortunately.
https://www.lemon64.com/forum/viewtopic.php?p=1024158&sid=d4a0af18517fc87193037a...