Nice game with nice graphics and really cool soundtrack. It was really fun to explore. I've got some issues, though...
First of all, I'd say that the lack of pixel rounding in 'retro' games is a cardinal sin. It really bothers me ^.^'
Second of all, the 'metroidvania' tag isn't fitting for this game. Backtracking with new abilities is essential for a game to be called that.
And lastly, the game is just very easy. The enemies are either too slow or too scarce for most planets to be challenging.
But other than that, it was a really fun experience and I don't regret 100%ing your game at all :3