Hey nice Little game it gives me some Age Of War vibes.
If I would have to point anything in the current version of the game that is "problematic" it would be that you can't loose...
To me it's not really fun to see the enemies Idling and not attacking my base. (is it something you plan to add ?)
if I let the game Idle for 30 / 40 min and come back I will be able to purchase every Upgrade and beat the game easily.
Alternatively it could also be a good foundation for an Idle/Incremental Game but in this case you should also be able to spend resource in economical upgrade.
overall good foundation for a casual game !