Galaxies Puzzle Online

Galaxies is a self-contained logic puzzle built around one clear objective. Each new board gives you a fresh problem to solve, so it works well for quick sessions and repeated play.

Divide the grid into rotationally symmetric regions each centred on a dot.

Left-click on any grid line to draw an edge if there isn't one already, or to remove one if there is. When you create a valid region (one which is closed, contains exactly one dot, is 180° symmetric about that dot, and contains no extraneous edges between two of its own squares), it will be highlighted automatically; so your aim is to have the whole grid highlighted in that way. During solving, you might know that a particular grid square belongs to a specific dot, but not be sure of where the edges go and which other squares are connected to the dot. In order to mark this so you don't forget, you can right-click on the dot and drag, which will create an arrow marker pointing at the dot. Drop that in a square of your choice and it will remind you which dot it's associated with. You can also right-click on existing arrows to pick them up and move them, or destroy them by dropping them off the edge of the grid. (Also, if you're not sure which dot an arrow is pointing at, you can pick it up and move it around to make it clearer. It will swivel constantly as you drag it, to stay pointed at its parent dot.)

Most puzzles in this collection reward deduction more than speed. Focus on the most limited choices first, use the clues to narrow the board, and avoid guesses unless the puzzle mode clearly expects them.

If you want the full original rule explanation, examples, and advanced options, the official manual is the best reference.