AbstractThe key element in the characterization, assessment and development of geothermal energy systems is the resource type. Throughout the past 30 years many resource type schemes and definitions were published, based on temperature and thermodynamic properties. An alternative possibility to cataloging geothermal energy systems is by their geologic characteristics, referred to as geothermal plays. Applied to worldwide case studies, a new catalog is developed based on the effects of geological controls and structural plate tectonic positions on thermal regime and heat flow, hydrogeologic regime, fluid dynamics, fluid chemistry, faults and fractures, stress regime, and lithological sequence. Understanding geologic controls, especially of geothermal plays without surface expression, allows the comparison with hydrocarbon reservoirs through their ratio of porosity and permeability. This analog has implications on site-specific, first class exploration strategies and reservoir improvement through technologies specifically suitable for unconventional sustainable energy reservoirs. This article aims to introduce geothermal plays to a wide geoscientific community and to initiate a geologically based cataloging of geothermal resources. With this new catalog of geothermal plays, it will be ultimately possible to transfer lessons learned not only within one specific catalog type, but also technology from geothermal plays to unconventional hydrocarbon plays and vice versa.