Nice game, it is a good take on a fairly solid mechanic. I give 4/5 because I would like to see achievements in game linked to ones erasable within NG here. Also, just looking at it from a logic standpoint, if you fail a mission, I would make the game display "retry" and "back" rather than "Next Mission". Not too much of a code change to do that especially since your "next mission" already triggers a replay. Other than that, nice work.