Hi, thank you so much for your words!
We wanted to submit more levels, but unfortunately we did not have much time given the logistics with family and other jobs, but it was the idea: that people felt how easy the beginner levels are and then get a bit stuck in the advanced tab for a while. We think we will continue developing this after the game, so we will definitely add more stuff!
However, we had not thought of boss levels at all, that is quite interesting and very much worth giving a try!
Thanks again for your feedback, we really appreciate it!