I have an new ideas to use effect accumulators and will test it tomorrow, but I must also add new functionality to effects accumulators, like value_multiplication_function = "simple, turn_activated, activated_count, activated_turn_count (and maybe others)". This value will determine how to multiply value. I must think on the idea yet.
The other idea is rules, which can be inserted into effects.ruleset. For example with event city_conquered, we could reduce production and happiness of conquered city for some turn.
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