Poorly-written code causes this game to throw up errors constantly. I have to clear caches and/or reinstall every time I play, and it usually says it's still running even though it's not. This is completely unacceptable for any professional game, even if it's "indie." I thought the developers would have been quick to fix these issues, but after several months, there is no change.
The game itself is a laid-back, casual arcade experience, which is a nice break from frustratingly difficult games that relentlessly punish players. However, the lack of any stakes means the game gets really boring, really quickly. The levels all feel generally the same, and the weapon selection is just about the only thing this game has going for it, and even at that, it still feels sterile after a short time. There's only a few types of enemies, and no bosses that I encountered. It's just a game that goes nowhere quickly and doesn't do much of anything to reward a skillful run or to hold your interest.
You get one game mode option. That's it. It's not even a quality game mode.
And for godssake, add some WASD movement support. That should be a bare minimum for any platformer game, or any game that relies on keyboard movement. I hate moving with the arrow keys, and my lack of muscle memory all but ensures that I don't get very far on each run. Also, can't you add even a simple volume adjustment slider? I know you're going for the retro thing, but we're living in 2014, and basic menu options should be mandatory.
In short: If you're going to do an ultra simple arcade shooter, you better put a LOT of interesting content in there, otherwise you give the player no reason to play it for more than 5 minutes.