In 1997, Wizards of the Coast tasked three designers with rebuilding D&D. The existing rules were a patchwork—percentile for thieves, d20 roll-under for attributes, d20 roll-over for combat. Cook, Tweet, and Williams produced the unified d20 mechanic: roll a twenty-sided die, add modifiers, beat a target number.

Cook’s prestige class is the clearest personal fingerprint—introduced to the DMG as campaign-specific exclusive roles. Widely adopted. D&D 5th Edition evolved them into subclasses.

Arcana Evolved (2003) introduced spell heightening—upcasting at higher levels for greater effect. D&D 5th Edition adopted spell upcasting as core mechanic a decade later.

Then Cook burned his own blueprints. The Cypher System (2015) reversed d20 philosophy. No modifier stacking. GM never rolls dice. Single-use cyphers. “I am a [adjective] [noun] who [verbs].” Authority split between GM and players, not the rules.

The Cypher System’s GM Intrusion—offer complication, player gets 2 XP—became one of the decade’s most praised innovations. Cortex Prime adopted similar mechanics.

One designer. Two philosophies. Both fully committed.

Total: 32 points. Year: 1990.

Both systems are still in play.