This is the Two Dimmensional version of the Slider puzzle. To play the game, move all of the pegs (black dots) from the top left corner of each slider to the bottom right corner. Moving a peg will block the progress of other pegs and unblock the progress of others. The more blocks are in the way of any particular peg, the darker the block appears. The darkness changes can are a big hint as to how the puzzle works.
What makes this version more difficult than the basic version is that pegs can be moved both sideways as well as up and down. This makes the puzzle somewhat more difficult. It's a good idea to master the Basic One Dimmensional Version before trying this one.
To move the pegs, just click an empty corner of the slots (white areas) and the peg at the adjacent corner will move there if it is not blocked.