Simpson went on to do freelance art for such comics as "Teenage Mutant Ninja Turtles" - "Teen Techno Turtle Trio Plus One!" ("Shell Shock") and "Tales of Alternate Turtles on the Moon" ("Turtle Soup" Vol.2 #2), Mirage Studios; and "Teenage Mutant Ninja Turtles Meet Archie", Archie Comics (1990) - and DC Comics' 1987–1988 anthology series "Wasteland" and "Flash Annual" #3 (1990). In his aforementioned works for Mirage, he introduced the superhero character "Pteranoman", intended to launch a new comic title, of which only one issue actually went into print.