Picross

I might have mentioned it in the past, but Mario’s Picross was one of my favorite games on the Game Boy Classic (although I got my own copy only in early 2003 and played it on a GBA) and I’ve solved these nonograms on paper in puzzle magazines, and played through quite a few games. It never seems to get old.
Currently I’m playing “Picross Fairytale – nonogram: Red Riding Hood secret” and it’s one of the hardest ones I’ve ever played. (The music is nice, too, but the “story” is a bit thin and gladly skippable”. It seems to be free to play still, so go get it.
There’s also InfiniPicross (played for 27h, got 22/22 achievements) and Picross Touch (played for 99 hours, 17/18 achievements, including one for 1000 puzzles done, yikes). Also both very good.
On Android I played Picross Luna and am playing Picross Luna II right now (but I don’t like their near-endless engame with like 100 puzzles that form a complete picture) and Two Eyes. All of them are pretty cool.