itch.io

You got a really good game foundation! Nice variety of weapons with different abilities, and also a decent size pool of enemies. The art and sound effects are also pretty nice.

Some feedback:
- A weapon switching animation would be really nice to have. Currently, the character looks the same regardless of which weapon he's using, and having different weapon sprites would let the player know instantly what weapon they have at any given time. Using number keys to select which weapon to equip would also be nice.
- It feels a bit weird having to use the mouse to select an upgrade, due to the game not requiring a mouse for the actual gameplay. There is a grab_focus() command for buttons in Godot which you should try to look into. This should allow the player to be able to use arrow keys to switch between the upgrades, rather than needing the mouse.
- The main thing that the game could use is advanced UI. You got everything you need, such as health bars, hit markers, buttons, text, etc. Using custom designs for them instead of Godot's base designs would really help blending your UI to the world better. 

That being said, what you made is really impressive given the time period! With a couple tweaks here and there, your game really has the potential to look very professional. Congratulations on your first game jam!