Color Labyrinth - A Smart Puzzle Like Sokoban  adds some very good elements to the old concept of sokoban. The goal in each is to move/push the blocks and get to the exit.
  1. Blocks that are the same color will merge. Sometimes that's a good thing, other times not.
2.  The grid is white. Black squares will sometime have to be filled. If a square is marked with a green +, that means that if a green square is pushed onto it, it will be locked in place.

There's a lot more to say about this game, but I'll let you see for yourself.  It's got everything: 'aha' moments, lots of levels etc.  I have not solved all the levels.

I'm not crazy about the graphics. But that's okay. The content is what's important. New elements are presented with easy levels and then things get gradually harder. https://itunes.apple.com/jp/app/color-labyrinth-cang-ku-fan/id451036454"mt=8

http://minimalie.com/

Other Good Sokoban Puzzles
A Good Snowman is Hard to Build Charming
Go to Gold - superb
Go to Gold 2 - I hope a third version comes out.
Pepe Porcupine
Sokoban Cargo
Push Box Sokoban
Push Around
Boxed In - loved this. First in a series of 4.
Pengu Push
BoxWorld - awesome. I still remember struggling through levels 26 and 35 for days.
Fireman Arcade
Paper & Light
Square Push Square
Professor Max
Puzzling Cubes
DJ Mole
Sokoban Evolution
Test Chamber - brilliant
Duck Roll surprisingly very good

Leonard Cohen died yesterday. My favorit...