I have a two monitor set-up which are usually set to 1024x768, which I believe is Aftermath's resolution, but the game wouldn't display and gave me signal over range errors on both of my monitors. I tried switching in a 1680x1050 native monitor, but got the same issues, which is maddening.

Along with not displaying, the game put up a rage-inducing refusal to close using Alt+F4 or the right-click option in my taskbar. When running it in my secondary monitor, this wasn't a problem as I could forcefully kill the task via Task Manager. When set in my primary monitor however, I couldn't kill the game with Alt+F4, couldn't click out of the game on my other monitor, and it wouldn't respond to Alt+Tab. When I tried to use Task Manager I was greeted with this wonderful visage (that white dot is my cursor). This persisted for several minutes, and my urge to smash things built up steadily.

I played around with the launcher's frequency settings, but it didn't help and decided to crash a few times. Then, for some reason, it randomly decided it was going to display, but whilst checking to see if it would last it went straight back to the same problem.

Anyone know what's going on?

I got the same problem and after some trial and error i fixed it.
First of all, this game only runs in 1024x768 resolution, so the problem is refresh rate not resolution. Because old CRT monitors run on higher refresh rate (~80Hz) than modern flat screens.
Changing settings in launcher.exe didnt seem to work, so I opened config.cfg in notepad and changed the line:

from
KEY "use_safe_refresh" BOOL FALSE
to:
KEY "use_safe_refresh" BOOL TRUE

Seems to work now. Hope it helps somebody.