Could you make like a loot storage box that is available across all characters? I find that collecting epic sets would be a fun thing to strive for. Also, harder enemies would be nicer.
A shared storage is kidna unbalanced since there's no level requirements on items, but you can swap hero at any time by pressing Esc -> Swap Hero. There's unlimited amount of higher difficulty levels with way more stronger enemies.
PRO TIP:Buying farms increases your population and max workers no matter what. Once you get the research center, use your knowledge to buy as many of max farm workers upgrades as you can. They will provide big boosts to your max workers so you can advance faster and further.
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A shared storage is kidna unbalanced since there's no level requirements on items, but you can swap hero at any time by pressing Esc -> Swap Hero. There's unlimited amount of higher difficulty levels with way more stronger enemies.