Don't worry about completing everything, if you can't. It might take a long time. The game is just iOS. In the future, I might look at Android though. You can make comments on testflight, or pm me or send me an email
Thanks for playing. You're right, once you master a level there probably isn't much chance you will be able to get a better time. So in that regard, there isn't much replayability. However, I think it will take a player a long time to master all 50 levels. It get's really challenging towards the end. I guess you're right about the redundancy of having another achievement after getting the five others. Thanks again.