The "Built to Rule" toyline was Hasbro's first attempt to break into the building block market cornered by Lego. Compatible with all major building block toy brands, these toys featured vehicles that could be built in two different modes, as well as a 3 3/4" G.I. Joe feature with specially modified forearms and shins that could attach to the blocks themselves. In addition to G.I. Joe, Hasbro also made various Transformers and Tonka Built to Rule sets.