Really nice game you got here! The music is the best part - creepy and space like. Took me a while to win on easy mode - the visibility mechanic makes it especially difficult and scary when an enemy suddenly appears right next to you! I actually didn't realise those big things I was shooting were the bases. I just thought they were a different enemy type and I'm too busy trying to stay alive to pay attention to the fact that the enemy bases remaining counter had gone down to zero. Perhaps add a bit of indication to highlight when you spot a base (as part of your tutorial?) and also a more flashy indication when you destroy one so the gamer feels satisfied they accomplished part of their goal? Really well put together! Had fun.