No this is not a tower defense game.
This is an action puzzle game with a bullet-hell twist based on getting quick times, collecting all the pickups, and not getting hit.
There aren't many levels overall 12 main levels with some sidequests[HLTB says 4 hours for campaign], and there are tutorial levels mixed in.
The graphics and soundfx fit very well together and emulate a 16 bit title well. I honestly wasn't paying attention to the music, the gameplay is hectic and it took most of efforts to dodge bullets.
I've had a lot of fun playing and I'll go back to finish the campaign. Getting 4/4stars on each level seems incredibly hard and I only managed to perfect the first level so far. I decided to write this because the helpful reviews filter was just awful for this game.
I think anyone who enjoys top down action, action/strategy or dodgy-shooter type games will like this game.