The D12 Only system is the original mechanic used to power Cyneric's Call. Designed to be streamlined and easy-to-learn, it allows for seamless transition in and out of fast-paced combat. As the name implies, each player only ever needs a single D12 dice to play.
Outside of combat, feats are attempted by rolling 1D12+proficiency in designated skill against a static 'difficulty threshold' that scales relative to the action being attempted. Initiative is checked by rolling 1D12+Agility, an attribute, for Player Characters and 1D12+level for Non-Player Characters.
In combat, players roll 1d12 to determine if they land a blow at all with difficulty relative to distance; if they exceed the threshold, the surplus is added to weapon damage and potentially other modifiers, then subtracted from the target's armor rating (if any), for total damage.