If you are looking for potential play-testers come check my discord. You can promote your project there.
Discord: https://discord.com/invite/jmf4pzv5Fj
Now to the actual feedback. I think passive income is broken.
After getting the first passive income mob the need too play the game is unnecessary. Maybe add a limit of how many coins a character can earn per level? As you upgrade the character the value goes down to 0 and you can continue making passive income.
Example: Character ears 10 passive income up to a total of 1000. After 1000 it stops and you have to upgrade him to level 2. Once he is level 2 the value changes from 1000 to 0 and you earn 10 passive income. Rinse and repeat until max level is reached.
I attached a picture of all final characters on max level with 54B coins and also in wave 3.
Thank you for the credit as well! Cant wait to see what else you make on your project.