ZIRKEL has been discontinued, but I am keeping this page up for archival reasons. I thank all the players and everyone who has supported the game! One message of a user especially stood out to me and made me very happy:

"I don't refer to Zirkel as a game. I use it myself to help with retraining my neural connections after a serious accident and experiencing a significant brain injury. This App is fantastic! The developer is very much interested in feedback and is incredibly responsive. Each level is challenging and helps to reinforce spatial, time, and logic processing. Plus it is just plain fun in addition."

This is not what I set out to do with this game but it felt very fulfilling that it could have this impact for someone.