 Discarded tiles are placed to the right of the player who discarded them, in a stack, so that only the most recent discard in the stack is visible.The usual rule is that you are allowed to look through all the tiles in the discard stacks to your right (the tiles you discarded) and to your left (the tiles you had an opportunity to take), but you can only see the exposed top tiles of the two discard stacks on the other side of the table.The object of the game is to collect sets and runs.