Man. I’d bet that this is another screen resolution thing. Rubicon isn’t doing anything particularly strenuous or taxing. The fixed one just looks for the best out of a couple preset screen resolutions that works and uses that. I’ll try and throw together a fix that will allow you to override it and run it at whatever resolution you want.
So… basically I’m using you guys and the demo as an alpha test? This is good for me. It’ll let me iron out these rather game-breaking compatibility issues that come up from running on a variety of different machines that are just almost impossible to simulate by yourself. Thanks 1000x for your patience, bug reports like this will make the game stronger in the end.
UPDATE: OK, I’ve set up an .options file that you can modify in a text editor to override the resolution RUBICON runs at. Here’s the new link. Let me know if it works out!