Liked the game. Pretty neat idea having to manage your speed and firerate by having to decide which one to bring back up.

I do have a few notes:

• Wasn't sure if you could indefinetly keep bringing up the speed and fire rate. There didn't seem to be any cost associated with it so found my self just spamming clicking until I maxed out the speeds.
• Would be great to see what the maximum fire rate and speed you can get up to. There seemed to be a limit of around 50 as spam clicking didn't get you above it. Being able to see it would be great I think. Would help with deciding if it's worth upgrading it again. If it was tied to a resource cost then this could possibly add a layer of strategy.
• It be nice to see a damage indicator for the boss. Didn't know how much more damage I had to do to the boss and all I could really do was just keep managing the speed and avoiding the boss attacks.
• And this is a personal one, but it be great if the upgrade buttons could be linked to a keyboard button when playing on a pc. This way you could keep moving and maintain a nice flow. Found that having to move off the play area which stopped the player in place to manage the upgrades made for both a bit of panicky play trying to make sure there are no enemies incoming and for these breaks where it didn't feel like I was doing much.

Would like to see this expanded upon into a flushed out game. I think it would be a wonderful game to play.

Great proof of concept for a combat mechanic!

Cool concept and I love the animated gif banner. This is a neat start and I think you could expand on this to make a galaga style space shooter!

 hope you will play my game and follow me too!