Baseline (Widescreen) Solution & Issues
Everything is anamorphic 16:10 scaled from an internal resolution of 320x200. The correct aspect ratio is always maintained.
Resolution support is very limited. The only resolutions listed in the launcher are 640x400, 960x600 and 1280x800. These are hard-coded so might not actually work in fullscreen mode. If a chosen resolution doesn't work in fullscreen mode the game falls back to a 4:3 fullscreen resolution; there doesn't seem to be any way to get the game running in a 16:9 resolution.
The internal resolution is always the same so use whichever 16:10 resolution is supported.
Ultra/Super-Wide (21:9/32:9) Specific Solution & Issues
Eyefinity / Surround Specific Solution & Issues
4k UHD Specific Solution & Issues