This is a really fun rougelike! I liked the puzzle-like inventory system and when you get a good run going you feeling sufficiently powered up, and when I died I felt the need to try another run which is the mark of well designed concept. The artwork is really nice too. I know its a game jam setting so time is very limited, but I have some suggestions if you plan on doing a future update:

• Enemies can spawn on top of the player sometimes (would be nice if there was some kind of 'no spawn' radius around the player)
• Enemies can get stuck on corners a bit too easily
• I think it would be nice if the enemy shooting sound differed from the players
• Enemies can still shoot after their death animation plays
• Sometimes the character can get stuck on walls and not be able to move
• I found the upgrade pieces were a bit hard to get 'clicked' in place at times and as the upgrade grid expands it can be hard to see which ones you picked up as they overlap the already connected ones
• This is a minor one but, on the browser the ESC key takes you out of fullscreen so I'd recommend avoiding that as a control if your game supports fullscreen mode

Seems like a lot, but its just because I enjoyed the game so much, really good submission!

The game is really good, and works well, i really liked the idea of upgrade through puzzle pieces.
But it felt a little bit too random, first game i got like 6 pieces or more by wave 4, second game i was at 5 pieces by wave 9. Or maybe I just didn't saw them because the can disappear ?
Anyway, it was really nice and the bugs looks cool, loved the variety.