Thank you very much for all your responses. I am currently working on the game so I have a hard time responding to every single comment. Those who have not received an answer yet: I didn't forget about you. I read every single comment. As a thank you I am going to give you a small teaser of the prestige update which should reveal a part of what I have planned. I am going to upload it as soon as it feels ready (could be tomorrow or even today). I don't want to rush it and break everything again. Thanks for your understanding. Image: http://www.fs-studios.com/games/perfecttower/teaser_0.06.png (graphics are not final)
A huge thank you for all of your feedback. This community is just awesome. I am going to release a balance-focused update tomorrow which hopefully fixes the out-of-memory issue too. For the prestige system I planned a blueprint-feature where you can pre-design a tower by selecting the upgrades you want to start with.
I have to appologize to those of you who might have lost a part of their score during to the changes I made to the save-system to make cheating harder. As an exchange you can claim all rewards in the bonus menu again.