The ATLANTIS Program seeks to develop new technical pathways for the design of economically competitive Floating Offshore Wind Turbines (FOWT). The program urges the application of Control Co-Design (CCD) methodologies that (1) bring together engineering disciplines to work concurrently, as opposed to sequentially, and (2) consider control-engineering principles from the start of the design process. By analyzing the numerous sub-system dynamic interactions that comprise the FOWTs, CCD methodologies can propose control solutions that enable optimal FOWT designs that are not achievable otherwise. Design optimization is defined here as the maximization of the specific swept-rotor-area per unit of total-mass (m2/kg) of the FOWT for a given power generation efficiency. The program offers a new Metric Space that quantifies this specific area per unit of mass and the air-to-electron power generation efficiency of the FOWT, and guides the research to navigate across LCOE (Levelized Cost of Energy) Pareto-optimal fronts. Projects in this program will cover three fundamental areas: (1) radically new FOWT designs with significantly lower mass/area, (2) a new generation of computer tools to facilitate control co-design of the FOWTs, and (3) generation of real-data from full and lab-scale experiments to validate the FOWT designs and computer tools. The program structure includes these three fundamental areas in two phases. Phase I, described by this document, is expected to cover the first two years with an anticipated $28M in funded projects. Based on the results achieved in this first phase, a second phase, subject to the availability of appropriated funds, is tentatively planned to be announced for another two years, with additional funds to continue the research in the three fundamental areas and with more emphasis on experimental testing. See Section II.B (Renewal Awards) of the FOA for further information applicable to Phase II funding.