I want to include some locked levels in my puzzle app as a lightweight reward system. The levels play relatively quickly (average 1-min/level) and there are 100-200 levels in a pack. I prefer not to enforce a strict sequential ordering of play (I'm worried that a "wall" of 200 locked levels looks somewhat daunting and does not allow any exploration).
I propose (for example) that the player must solve puzzles #1-4 (in any order) to unlock #5, #6-8 (in any order) to unlock #9, #10-13 to unlock #14, and so forth. The locked levels have no dependencies other than you must solve those puzzles immediately preceding it and after the last locked level (e.g. you can unlock level #9 without unlocking level #5).
While I don't expect to convey all the subtleties/rules of unlocking, would the following graphic be "good game design" practice for showing the locked levels? Would one reasonably assume they had to solve #1-4 to unlock #5? (I know that this a subjective question, but game design psychology can be a pretty subjective topic).