Space imagery is mostly dark with bright structure running through it, which makes for a striking finished picture and an unusual solving experience. Nebulae give you colour to follow; star fields do not. Working one of these is the strongest case for turning the reference image on — and for a dark table, so the puzzle is not floating on glare.
A star field is the hardest thing on this site — near-uniform dark with scattered points that carry almost no positional information. Nebulae and planets are much friendlier, with strong colour structure and a clear edge to build from. If you are new to this category, start with something that has a planet in it and work up.
Difficulty: Medium to hard. Large black regions are unforgiving. Every picture here is graded automatically by how much its neighbouring pixels differ, rather than by subject — why that is the thing that matters.
Pick any picture below, choose anywhere from 12 to 2000 pieces, and play free in your browser. Share one link to solve it with friends on the same table, or use a photograph of your own instead. Browse every category.