The DPMI error is because you need to download CWSDPMI (or run under Windows 95).
As for the dosbox-x, crash, that's really odd! I've tested on 486s and Pentiums, but there's always a chance a bug sneaked in. I will look into it.
Thank you for your interest...but please, bear in mind the grunt of the work done for this game was only a 2 week effort 😇
Edit: Ah yes, as for the authenticity, I think Trixter said it best: this deserved to be a Real Mode game. But given that this was one of my first DOS games, it is protected mode (386+) instead. At least I eventually did make a 8088+CGA game, but damn, it was hard work!