FillField

The complexity of this puzzle is determined not by the complexity of the rules, but by complexity of the task. Rules are trivial: there is a rectangular box filled with dual-position switches. When you change the state of one switch, this leads to a change in the status of some (what exactly -- depends on the settings of the game) nearby switches. Goal of the game is to set all switches on the box in same position.

You can get free version here: https://play.google.com/store/apps/details?id=org.asciigames.fillfield_free