My game refuses to run in any reasonable resolution. I try setting it to 1440x900 and 1280x1024 and the game stays in the tiny 800x600 or 640x480. No errors saying it doesn't support the resolution, it just wont work. Both in windowed and fullscreen.

Anyone else have this problem? Or maybe a fix?

No that's actually a feature.
It sets the game in half resolution of fullscreen, so you can play fullscreen in 2x like it was intended.

Fullscreen x2? What is that?

But the game also halves the resolution in windowed mode

The game's art style isn't to fit a super large amount of stuff onscreen. It's pixel art, so it's zoomed in so that you can enjoy it.

I'd really rather see what's going on then the art.

Not dieing > Pretty colours

That's the problem, you can't see what's going on when your soldier is the size of a housefly, which he would be if you ran the game at an unintended high resolution.

The game intentionally scales the game by 2x with point clamping to preserve the pixeliness (as opposed to linear clamping, which would be rather blurry and is what happens when you play the game at a lower-than-native resolution).

EDIT: Data explains.