Really nice game... You can try using valve's alpha tested magnification based on distance fields to increase the quality of the vector art, so that the textures don't get blurry.
Sorry, but for me this game deserves a 2/5... Causes:
- Serious lag after navigating trough 20 bubbles or so
- Overcomplication of "upgrades", should be easier to decide (ie: you can upgrade 6 qualities - speed, firerate, spread, ...)
- Overcomplication of save/load... When I load the game, I just want to be exactly in the same place I was last time (server-side)...
- No instructions... I have to wonder randomly... I can navigate to bubbles with enemies really powerful... Better to have a route or other stuff..
- Boringness