This is a funky error that pops up with unity games from time to time, and I have no idea why. The full text of one might be something more like this:
Switching to resolution 1920x1080 failed, trying lower one
All resolution switches have failed
Screen: could not switch resolution (1920x1080 fs=0 hz=0)
It's something that has come up as far back as 2011 with AI War Classic, but only with one customer ever who reported it (!), and as recently as with Starward Rogue with again one customer (different person). Dead Island and a few other games also come up when googling this, but again extremely rarely.
Often a reinstall of the game, or a validation of the files, or even just a reboot seems to fix the issue. In some cases it might be out of date graphics drivers, or something funky with multiple monitors or virtual monitors. For the record we all run multiple monitors here at Arcen, but typically only on our windows boxes. OSX has some funny bugs with multiple monitors depending on what exact version of OSX you're on. Thankfully those haven't been much of an issue since I believe 2012 or so, I want to say.
At any rate, the simplest solution is to run the game in windowed mode. With AI War 2, the way to do that is to take the attached file, and put it in the PlayerData folder inside your game folder. Things should load fine from there, and you may even be able to run fullscreen afterwards.