5/5. Good game. I suggest you get ranks at the end of the stages based on challenges or kill ratio, that make you wish to come back and play some stages again with more upgrades, also some badges would be good.
Just get all upgrades in the priority speed (1st) then protect, then regen. In that order. The last upgrade get "total vacuum". Now you have an immortal gigant worm if you just spam space and keep it a little above the floor. Got 1k combo then got tired.
...Bad music, shitty graphs...Couldn't even keep listening the music and waiting game start...So, i scrolled down to write a comment. Then i became curious and looked up again to see the game...I played and got lot of fun. Good Work.
But really, u could make the music better.
The boss arrival counter goes up as u kill enemies, so u can maximize your gold/profit by leaving weapon and fire rate upgrade to last. Upgrade Order Suggested (To get the last badge), assuming u already finished the game: 1- Max Treasure; 2- Max Banner (So u maximize the loot) keep running in circles and keep focused to get treasure chests
upgrade 3- Max Sails; Lastly upgrade weapon power and fire rate. With that u should get a lot of money and prolly can run max ship w/ max ups to get last badge easier.