Puzzles for adults come in all kinds of shapes and sizes. Jigsaw puzzles for adults cover a litany of subject matter, complexity, shapes, cut styles, and methods. While you can get anywhere from 250 up to 32000-piece jigsaw puzzles, there are lots of adult-specific, fun, engaging, and challenging puzzles within the 1000 to 2000-piece range.
There are also 3D puzzles for adults. While these are not technically jigsaw puzzles, and their piece count is significantly lower than most jigsaw puzzles, 3D puzzle piece shapes and configurations are largely the same as their 2D counterparts'.