There's not a hover-price for Eternal Cores. There's no known time taken for the various crafts, just changing from one unknown number to another with each upgrade. The prestige percentages are rather low, and do not state what they do. This is unfortunate considering how much time they take to reach, and do not encourage use due to not adding anything not present before it.
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Thank you for the detailed feedback! You made some very good points.
I’ve updated the game so Eternal Cores and all other materials now display their sale prices clearly. Machines also show their exact craft times, and upgrades display the current value compared with the value after purchasing the upgrade.
I also significantly improved Temple Awakening. The first awakening is cheaper, awards more Relic Shards, clearly explains what resets and what remains, provides stronger permanent bonuses, and unlocks new milestone rewards such as improved Overdrive, bonus starting resources, Auto-Overdrive, and doubled Eternal Core value.
Thanks again for helping me improve the game!