Adam's Ring app for iPhone and iPad
Adams Ring is a puzzle.
Each puzzle is made up of coloured discs in slots spread along interlinking loops. The discs are mixed up to start - the objective is to return each disc back to a slot of matching colour.
Where they interlink, discs can move on more than one loop. Touch the screen to activate the nearest disc - and drag to pull a loop of discs. If the activated disc lies on more than one loop, the direction dragged will determine which loop is pulled.
Simple - huh?
Oh - and there are wormholes in some games now too.