Thok barrier

A Thok Barrier is a sector with the floor and ceiling heights the same, surrounding a level. The term was first coined by the Sonic Robo Blast 2 community when it turned out that Sonic the Hedgehog's "Thok" attack moved him fast enough to go outside the single-sided Linedef borders of the level. The only way to combat this was to make all the border lines into double-sided linedefs.