Took me 3 games to figure out how to attack the boss (and I notice its live bar only at the second game :P).
The game is quite simple, perhaps adding different enemy attacks with different speed/ behavior could have made the game a bit challenging and give it replayability.
Once the boss is being hit twice the game ends and when you know what to do you don't feel like playing again.
Good attempt that can lead to a better game :-)