Interesting gameplay idea. The controls could need more polishing, both me and the enemies often gut stuck. The enemies are attacking the air a lot. The controls and the goal of every level are not really explained, sometimes you can plant crystals, sometimes turn them into friendlies, sometimes you have to destroy all enemies, sometimes fill all crystal slots.
I lost in the level against the big ones, that one had way too many enemies. No idea what to do there.