I really liked the enemy design, the glowing eyes, letting you know they are there but not which kind. The pacing was off, some waves were good but others had nothing then all of a sudden I'm surrounded by a dozen. It took me a few minutes to realize that the attack is ranged, I thought clicking just aimed and it was melee. I had been clicking in the dark, where the slash didn't show up (but thankfully still did damage if the enemy was partially lit).
Also, I love that you actually gave a little tutorial and intro sequence. Nice work!