This is a nice looking game, I can tell a lot of visual polish went into it! I think if you want to expand it, you might want to play a few more top down twin stick shooters to get some inspirations. One of the tricky things about it for me was the general convention for control in these games is that WASD moves and arrow keys shoot, so this was actually really hard to wrap my head around. Also the controls could be tightened up a bit, they felt really slippery and you move much faster horizontally than vertically, and your small bullets make it very hard to hit enemies especially those tiny slimes. Overall, I think the visuals and sound of this game is really great, and with a bit of tightening on the controls you'll have a great game on your hands!