The game looks good, theres just some small problems with progression where it takes away too long after you reach level 3 or 4 on buildings since you will need to idle far too long to hold interest of most people, since you will have nothing to do other than waiting resources to pile up enough to make the next building or wait hours for the construction to end.
I think that builders slot should be a lot more common like 1 from every boss that way people can start multiple buildings and mix between some fast upgrades with the ones that take 6 or more hours, because even with 3 builders its quite slow when most of your upgrades take more than 2 hours.
It would be nice to have a lot more enemies bellow 1m attack since those are the ones that help more to reach end-game (the wizard spells), after you beat the ones bellow 5m the others are just too strong and require dozens of battles to beat.
Maybe the game could have a rebirth system with increased amount of builders and decrease in buildings prices, that way scalling could get faster and faster.