NoahT wrote:
IIRC, I think there are even some mutually exclusive challenges.
there is one such pair I can remember - but, yes, one can complete 100% of challenges, and have only one play-through. I went back and restored to rooms to do their challenges, and still had them when I restored back to my 'most progress' save. In that way, challenges are like secret rooms (and unlike optional non-secret rooms).
If a secret room happens to also be one you can backtrack to, then restoring to it, then restoring to a later save, then backtracking to it, will still show it unconquered -- but in terms of hold mastery, you have beaten it. (If this paragraph is confusing, ignore it).
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