The GPL code will remain here for the duration of the game jam, since it would be unfair to re-upload the binaries. After that I'll take it down since I wrote my own class to fade the screen (and with fancy transitions too).
Additionally I was mistaken about the cat & mouse graphics being GPL (graphics from the Scratch project are licensed under CC-BY-SA).
This should cover all previous GPL dependencies. The code in the git repository and the new code archive is licensed under the MIT license.
I hope this is OK.