I had a fun time solving Patrick Berry's puzzle extravaganza "Containment Policy." It took a while to get through. The puzzles were pretty straightforward to solve, but then I spent a while staring at each one trying* to figure out how it was constructed. These puzzles solve kinda like crosswords, but with different topology. The instructions are generally something like "Solve the across clues; you'll know when you have the answers right because each square of the grid is covered by an across-answer and by a something else answer." And the something else gets weird and interesting.

*Unsuccessfully