The Threshold System is a tabletop roleplaying game core engine centered around a “Roll-Under High” single-d20 resolution framework. Players perform actions by attempting to roll below or equal to a fixed character skill rating while simultaneously exceeding a minimum target quality value. By utilizing a strict cap on skill ratings and adjusting difficulty through target values rather than variable roll modifiers, the engine keeps mathematical scaling predictable across any setting. Outcomes naturally generate distinct narrative results, allowing for critical triumphs, high-quality successes, or “success at a cost” when a roll falls under the required minimum quality.

To handle challenges beyond simple task resolution, the framework relies on parallel visual trackers—often represented as clocks—to monitor various forms of stress, damage, or degradation. Physical injury, mental or social composure, and energetic strain all utilize these synchronized tracking loops. Equipment and gear are governed by explicit durability mechanics that trigger wear and tear during high-stress usage or tactical defense. Because these resource-attrition systems function uniformly across physical, social, or mental obstacles, the engine maintains high-stakes tension and tactical depth across any narrative context without requiring separate, genre-bound rulesets.

Because the resolution engine relies on abstract mechanical structures rather than genre-specific flavor, it easily translates to any setting that emphasizes grounded consequences and strategic resource management. A GM can repurpose the strain tracker to represent physical fatigue, mental trauma, neural overload, or magical exhaustion depending on the world's themes. Similarly, social debates utilize the same structured conflict framework as physical confrontations, giving non-combat interactions the same tactical weight. Players can actively adjust their risk levels prior to rolling by declaring harder minimum targets to gain greater mechanical benefits, allowing the system to model tension, tactical risk, and high-stakes drama universally.