My only issue with this particular tech is that I did not realize when I entered that age that it was a diamond tech, and I wasted some FPs on researching it before I learned that. I had misassumed that the diamond cost given was what it would cost to unlock/research the tech IMMEDIATELY (as they give the option for with many other things, including, yes, researching/unlocking techs). Plus, there are probably some users who don't understand that it's an optional tech they do not need to research; until recently I thought you had to research everything in each age in order to move to the next age. :unsure:
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I don't mind it being a premium tech...I just wish it'd be removed from the tech tree, or else that they would make it much clearer (maybe by "disconnecting" it from the tech tree proper?--so it floats all on its own or something?--like a falling leaf?) that it's optional and it WILL require diamonds to unlock. Just so other saps like me don't waste FPs researching something we'll never unlock or use. :hmph: