Nice! The game feels very well made and complete. Small bugs: 1. Cash sometimes doesn't appear until an upgrade is purchased. 2. Velocity and distance don't match. "Space stars" make up for it though. 5/5. Great job!
Got a few achievements left...i guess they are:
Score master V
Money maker VII
Money Maker IX
Anyone knows whats required for these?
Guess the last achievement is for completing all the other
 "Flight"){kind=icon}
 "SteamBirds"){kind=icon}
 "mini Tower Defence (mTD)"){kind=icon}