Last April, I completed all 50 levels of Sokoban which was very enjoyable.
The game can be played on the web and involves moving boxes around the
playing area by pushing them only. I have started repeating the feat as it
took so long for me to finish the 50 levels I have forgotten the solutions.
Got to this link for the game info.. http://www.cs.ualberta.ca/~games/Sokoban/