Nice! After playing a while the whole screen turned black...

You've got a really good start here, I liked the art and game-play was surprisingly responsive. These survival top downs don't usually have something to defend, so i actually liked that idea. Enemies ramped up way too fast, though. It should either be possible to repel them all without the crystal taking damage, or the crystals health should replenish each wave. It just feels impossible currently.

I survived from the first wave.

I could not beat wave 1! Needs a slower ramp-up.

Really nice game! I really like the fact that enemies drop a ton of coins and felt like it was a tradeoff between getting coins and protecting the crystal :)

It seemed I couldn't protect my crystal from being damaged, no matter how I played. Is there some strategy that I'm missing here?

The controls were a bit weird at first. But I sort of got the hang of it after several attempts.

It's hard.