This iterative game series (each building on the one before it) has gotten to some pretty clever puzzles. I especially enjoy the puzzle that leads to (mild spoilers (Spoiler - click to show)the axe).
Implementation issues are rife, though. To complete it, I had to use the follow non-standard verbs (moderate spoilers): (Spoiler - click to show)SNIP, use BLANK with BLANK, and POUR.
While the increasing puzzle size has made the game quite a bit more enjoyable, I almost with we were seeing multiple levels of polish and implementation instead, with less and less bugs and more fanciness. But the problem with that is that minimalist content is easy to add; its complexity is linear, with a small change in size requiring a small change in coding. But smooth programming is quadratic; making a very polished game requires coding in tons of interactions between different items and things, adding responses to everything players try, getting a lot of testers, etc. So I'm not sure it would work in practice to show that through a series of games.