I like the idea of attacking by drawing shapes, but the controls are a bit unwieldy. I keep forgetting that I need to hold W to keep going, maybe drawing should let you maintain your speed? I didn't understand the time shift thing at all, didn't notice any change when pressing RMB. Hitting the ground was devastating, it costs a few seconds while enemies are ramming bullets into you. It really sucks when the game doesn't register a big shape too.
Consider trying mouse controls where the ship follows your mouse and the further it is, the faster it goes. Maybe add a button to slow down instead of speed up because from what I could tell, you pretty much want to always move?
I can imagine this game being really fun in the future with some refinements