The art, music, and sound effects are excellent, but it doesn't look like there's a whole lot of gameplay at the moment. I tried the bow, crossbows, gauntlet, and staff. I kept getting stronger with each gate, but I barely took any damage from enemies.
In the Options menu, there are left and right arrow buttons for increasing/decreasing the resolution, fullscreen, etc. You can press the same button multiple times in a row to cycle through the available options, but it doesn't look like this works for the "Retro Filter" button. I assume this is unintentional. You might be changing the position of the button so that it's no longer under the mouse.