Sorcery
Exile all creatures. Each player creates a 0/0 green and blue Fractal creature token and puts a number of +1/+1 counters on it equal to the total power of creatures they controlled that were exiled this way.
If a commander is exiled this way, its power will be counted along with the other creatures. Once Oversimplify finishes resolving, that commander's owner may move it to the command zone.