About Rotos
There are 10 round moving pieces held inside, visible through holes in the puzzle frame. Each disk holds 7 of the pieces - one in the centre of the disk and 6 arranged around the rim. Each disk can be turned(pressed) (by multiples of 60 degrees), so that 6 pieces are cycled around by a move. In the solved position the top row has red pieces and the numbers 1,2,3, the middle row is yellow and 4,5,6,7, the bottom row is green and shows 8,9,0.
This is simulator of original puzzle (invented by Manfred Fritsche, and patented on 4 June 1986), but it's unofficial version and neither the game or the developer is endorsed or related by inventors in any way.