I would like to set the resolution of the game to be either proper fullscreen at 1080p or a smaller window resolution to better fit my monitor. But the options menu only has sound sliders -- resolution options nowhere in sight -- and the game launches in 1080p windowed mode.

ALT+ENTER doesn't work to enter proper fullscreen, and the game won't let me resize the window size with the mouse cursor either.

In this day and age resolution options should be standard for any game, but not here.

The developer Gambrinous posted a response on Steam regarding this issue here, saying: Another user reports that you can apparently also modify the shortcut to force fullscreen mode, like so:

thank you