Complex sentence: The game rules for Underground is an adaptation of the Mayfair Exponential Game System, originally developed at Mayfair Games for the earlier DC Heroes roleplaying game depicting the DC Universe, however the rules were modified to depict lower-powered characters and a more deadly setting.
Split into simpler sentences: The game rules for Underground is an adaptation of the Mayfair Exponential Game System, originally developed at Mayfair Games for the earlier DC Heroes roleplaying game depicting the DC Universe. However the rules were modified to depict lower-powered characters and a more deadly setting.