Thanks for trying it out!

I just updated the game with a new version that checks if enough time has passed since the last frame in OpenGL mode. Could you please try if that makes it playable?

@JC_, thanks for your hints, however this game was originally written in 1998-2001, first intended for DOS, later I added a kind of "emulation" layer for Windows, internally it is still using 320x200 mode with a 256 color palette. I would do many things differently if I wrote the game from scratch now (and I'm working on Charlie III). But here I'm just trying to get my old game onto Steam.

BTW: during the game you can Ctrl+Shift+R to show the framerate.