Dark Light Swap

In a minimalistic black and white world, you have to control two emoticons - dark and light. They move across a black and white field, each in the opposite direction. You need to get both of them into the portal. To do this, you will have to build complex movement patterns and change characters from time to time in order to pave the way for another. If something goes wrong, you can undo the last action or completely reset the level.