Spawn 100000 enemies - get free kills.
A decent start, everything is light and immediate, no move feels like it has any weight to it.
Also no cooldown on anything make the game as easy as fast you can mash out buttons, if you're good enough, you can just dash in a circle and never get hit by a million of enemies.
I couldn't find a lock-on, which could be a make-or-break feature in this kind of games.
It reminded me of Z.O.E. a lot, you might look there for an inspiration.
P.S.
Enemies seem to flock together when you die, pretty funny looking.