I was shooting at someone, someone was shooting at me, I was receiving some 'bonuses,' and no matter what I chose in the scene, it had absolutely no effect.
I had to spend time searching for information on how to use what I selected, if it was even possible.
It definitely needs a bit more polishing.
Yeah, a lot of stuff was implemented very poorly, and by the time I had finished the main gameplay loop (attacking, enemies, waves and rewards), the development time was pretty much over.
I'm guessing that that the reason for the screen being like that is because of the resolution you were playing on. It seemed fine on my screen, so I honestly forgot to account for that. Testing right now, and yeah the problem does happen to me as well if I make the screen smaller. 
The settings menu not showing any options is not a bug, just me not managing to add anything to it in time. I meant to add sound effects first and then add sound sliders, but ended up doing neither.
For the abilities you selected to take effect, you need to first press tab to open the inventory, click on its icon in the left part of the inventory, and then click in an empty space of either the attack or special-attack grid. But since the inventory is broken for smaller resolutions as well...yeah.
