Good game to play for those who are looking for reaction time challenges.
My recommendation is that:
There should be indicators on where the player should move the spacecraft on the map in the beginning levels of the game. I got confused by the "What?" and "Start" squares. As a new player, I thought that the Start square was the beginning of the level so I tried hovering towards the left to see the other levels.
Also, there should be an indicator in choosing the upgrades. I suggest changing the colors or other creative methods for the color-blind people to determine if the upgrades worked or not.
It is a fun and challenging game with a few tweaks it is going to be a huge hit. 5/5