I stopped playing it at "42.04k years" (Phase 4). I felt like there was too much manual clicking. The story is quite cool so far.
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I thought the same thing at the same point, and I wondered why the idle activities were becoming more and more useless. Then I discovered that if I actually went back and finished off the first couple of activities, instead of maintaining proportional spending, then more activities became available, the manual activity shifted from "walk" and became stronger, and the pace of gameplay became reasonable again.
So I don't really think the balance itself needs all that much changing; rather, there needs to be better signposting that completing all 100 levels of the early activities is a thing that should be done when possible.
Thank you for playing, and for taking the time to write this up — it’s a real pleasure to read.
You actually found the intended rhythm exactly: finishing the early activities completely is what unlocks the next ones and turns the manual action into something stronger. Honestly, I think I’ll keep the signposting light on purpose — working out the efficient path for yourself is part of what I wanted the game to be, and you did exactly that. Really glad it clicked for you.
Thanks again for sharing this!