The Atomic RPG System is a d20 system. Players will use a twenty sided die (d20) to determine success in things such as attacking and skill checks.
In the Atomic RPG System higher numbers (stats) are better than lower ones. Atomic RPG System character stats will added to modify the d20 roll. Success or failure are determined by a specific number which is set by either the stats of a challenger or by the Game Master(GM).
Rolling the target number or higher equals success. Rolling below the target number is a failure.