How do I unlock more levels in Co-Op?
Solution 1:
Finishing all of the levels in a category will unlock the next one. So in your case, if you finish all of the levels under Mass and Velocity, you will unlock Hard-Light Surfaces.
Finishing all of the levels in a category will unlock the next one. So in your case, if you finish all of the levels under Mass and Velocity, you will unlock Hard-Light Surfaces.