 Some 4th edition rules enhancements for the setting include new damage types such as "Radiation", Gamma World-specific skills, and increased lethality.Despite these differences, it is possible to use characters and monsters from a "D&D" game in "Gamma World" and vice versa.The original "Gamma World" boxed set (containing a 56-page rulebook, a map of a devastated North America, and dice) was released in 1978.