Hmmm, nice game. Progression is too linear, when there's too many factories, the game starts lagging. At about a quarter or less of all the building area filled with factories, the game becomes unplayable. You might wanna check on that (there are optimizations to this very problem on most engines)
Suggestions:
As many stated, the progression it's too linear. Try decreasing the profit per cost on each tier. That way, you can create an efficiency vs space constraint problem.
As for information, building count and slime rate is appreciated. Also, mentioning you get refunded 50% of building on demolition button is nice. Btw, the button is missing the last letter. If it's due to clipping you can either add more space or decrease the font.
Since there's no use for the slime rather than selling them, you can either make the factory produce the coins directly, and leave the slime to the lore; or you can effectively make the factories more functional, ie: the slime generator producing slime balls, which then gets compacted/refined/processed into more profitable tiers/items.