For the record I beat the whole thing, at it's core this game is very fun! I do have some feedback:
Time limit is way too brutal. I read you wanted the game to be hard, which is fair, but it could be achieved some other way than kicking the player back to the beginning if their first launch isn't pixel-perfect. Maybe extending the time limit to a minute, and opting to giving a score to the player depending on how much time they had left or how many launches they used (like golf i guess).
Also the launch mechanic could use some more feedback. It took me a while to understand I had to move the cursor out of the game window itself to actually give enough power to the launch to really get anywhere. For example arrow becoming longer to show the variance in force.
Still, for our time limit you did very well with this! I get that in a week you don't really get much time to iron out everything - neither did I. I would love to see this developed further! Good job!