Idea
A simple idea, make generators unlockable for the price of other materials, adding a more linear progression of items and a few more strats.
More Info
You start with your home generator making iron at the same speed, but it also makes 1 gold for every 5 iron. Once you have 5 gold, you bridge to the diamond generator, upgrade it, and it immediately dispenses a diamond so you can upgrade your base generator. You grab a bunch of diamond while gearing up, and head to Mid. Only one emerald generator is on. Someone’s been here already and has upgraded a gen, probably to get their own base gen to the max upgrade. You turn on the other 3 mid gens, for the cost of 8 diamonds each. Now, you have enough emeralds to upgrade your base generator to max (5 diamonds then 8 emeralds).
Notes
Keep in mind, these proportions and such are only me spitballing ideas! I’d be glad to see this implemented even with many changes. This topic also contains some ideas for base gen upgrades, but those aren’t necessary; I just think it works a bit more smoothly with the main change.