Thank you so much for playing!
The exclamation mark is the place where you'll find the final boss, and it's hidden for a reason: I first wanted the fight to start as soon as you reach the place, so when you don't know where the boss is, this works like an ambush. There are ways to know it and play to your advantage for better planning. But I might make the location visible at least in the first level.
I think you missed the shops, where you can find greater upgrades, like the laser you said and other weapons. I think I should made more clear when the ship is in a special place, for better visibility.
The exploding mines per-se are powerless and boring enemies, I'm planning on making enemy encounters more interesting by combining different waves.
I value your feedback and it'll help me make a better game, for sure. Thanks!