It is fun! I found the skill jump to be pretty steep when new enemies start getting introduced. Also it would be nice to have a short description for each of the upgrades.
Glad you enjoyed! Yeah, the difficulty was a bit too high, so I'll have to tune that some, and the upgrades do definitely need descriptions - your game does a good job with that - but I ran out of time after making the boss and couldn't add that. Thanks for playing!