Thanks so much for this feedback!
I am glad that you enjoyed what we have been cooking up for the past 2 weeks! :)
And yeah. The difficulty spike might be too steep because some safe zones are wrongfully defined as endgame danger zones :D
As an additional note: if you want to, check the bugfix version of the game. The small towers now have a failsafe mechanism that still make you progress the game in case you encounter a spawn bug :)
Bottom zone is easy.
Left zone is medium hard.
Right zone is hard.
Maybe this will help you finish the game. I would really like to know what you think about it after finishing :)