Thank you so much for such detailed and valuable feedback!
I really like the idea of scaling energy regeneration with the ritual number / solved puzzles, because it keeps the progression under control while still making the player feel constant progress.
Thank you for taking the time to explain the problem and suggest such a clear solution. I will definitely implement these suggestions in the next parts of Runecaster.
And thanks for the other suggestions as well - they will make the progression much clearer, improve the puzzle flow, and reduce unnecessary waiting.
I really appreciate it!