All WIP obviously (and the walls need to be taller) but I think I got hitscan working the way I want it to (I'm happy because I've tried and failed before) . Any projectile enemies will probably be slower moving and dodge able, but I want player weapons to feel punchy and strong, and I think in a smaller environment instant hits add to that. The guns now only visible when aiming with arms for running. Probably should have a different sprite for aiming while stationary.
For the code curious, the "projectiles" are draw backwards from the impact to the barrel, so the image_xscale can be reduced to create the effect of motion even though the hit is instantaneous. I use 9 slice repeating the center of the shot, with the start and end only encompassing the impact and shot (though the flare is a particle).