Other coder was lured into the trap of RNG for puzzles, but only had time to make 4 puzzles, so the 25% chance did not work in your favour. More are being cooked up but we should work on having the random system more refined.
Funny story is that Nug wasnt supposed to be an npc, instead he was a reward for the level that is part of cut content, but now he is cut Ph'nglui. In a future update I want him to actually accompany the player