Excellent post. Persuaded me to get that CC and raise it to level 70.
Inspired by Laozi, I did a similar analysis for the Himeji Castle and Space Carrier. With the same assumptions. For comparison I included CC, Inno and BG with a 5-fp return. Also added BG with an average of 10-fp return on double collection, which should now be feasible with all the newer special buildings.
HC
HC and SC on average gives 18.5 FP as spoils_of_war when paying out. (10*0.25 + 50*0.12 + 200*0.05 = 18.5).
The expected average payout is thus 18.5 x P(spoils_of_war) x N_attempt.
Data for HC and SC grabbed at wikia.
Results
The figure below shows the time needed to reach break-even as a function of GB level. Legend: Himeji Castle (HC), Cape Canaveral (CC), Innovation Tower (Inno), Space Carrier (SC), Blue Galaxy with a 5fp average double reward (BG-5), Blue Galaxy with a 10fp average double reward (BG-10)
The overall conclusion is that
- CC is still the GB with fastest break-even on invested FP.
- BG with an average of 10 fp payout on each double collection is (as predicted) the second best.
- BG with an average payout of 11.6 fp or more will become the best FP with regards to break even on FP investment (not shown in figure).
- HC at level 41 is almost as good as Inno at level 65.
- The curve for HC is "flat" from level 20 to level 58. So why not take it to 58, and optimise other benefits from it?
- SC has same payout as HC only its a little more expensive, so it takes roughly 25 days more to reach break even.
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