So it looks like you can get infinite upgrades by buying other items than the one you got to 10. Buying the 11th will stop the upgrades.
Took my soda bonus to 2000% and quit.
The clicking/2x was a nice thing. Not absolutely necessary, but gets you to the end faster.
I don't speak german much and not entirely sure what the game was about, but seemed like the game could have part 2 after the first part. Colonize a planet and change the game mechanics a bit so it won't be the same stuff with different pics and text.