I really like this game idea : that's a pretty simple horizontal Space Invaders like game, but the different modes, and the interactive tutorial made it even better.
The art was nice, the sounds were good too (mabye the SFX were a bit too loud sometimes).
A little thing is the contrast of the black ship (the enemy I seen the most often) : it's black on a black background, and the outline doesn't help enough.
I'm pretty sad you lacked of time to finalize the 2 other modes and some more enemies, but I'll for sure play them when you post an update.
Good game !