Huh, if you mention radioactivity - do you already have the ability to assign engineers to the plants? Because if you do, you definitely want to ditch coal or oil and focus on the other - engineer working on a plant gives it a major production boost.
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Well, having to be smart with your engineer placement was intended a bit, so you would never actually have enough to fill all those 10 slots (but, to be honest, most of them are not needed - you only need the plant that is the best for you at this moment, for instance).
The engineer cost scaling is 100 (the cost of each next engineer is 100 times higher), but it is divided by the population squared, so the population has a big effect on the cost. It was probably a bad design decision, since it is hard to recover if you lose energy output.
I can see the game potential but with the current balance is not fun.
I hope to replay the game after a rebalance of things, I know you will not do it now because how the Jam works and I agree with this decision. Good game with some balance problems. Good luck to you and I hope to see more content from you.