The Lunar Occultation Observer (LOCO) is a new gamma-ray astrophysics mission concept being developed to probe the nuclear regime (~0.1-10 MeV). LOCO will perform an all-sky survey of the Cosmos at nuclear energies, and will have the capability to address multiple high-priority science goals. Placed into lunar orbit, LOCO will utilize the Moon's unique environment to maximize performance relative to terrestrial endeavors. Specifically, LOCO will use the Moon to occult astrophysical sources as they rise and set along the lunar limb. The encoded temporal modulation will then be used to image the sky thereby enabling spectroscopic, time-variability, point- & extended-source analyses. This Lunar Occultation Technique (LOT) enables the excellent flux sensitivity, position, and energy resolution required of the next-generation nuclear astrophysics mission. In addition, occultation imaging eliminates the need for complex, position sensitive detectors. The LOCO concept is cost-effective, and has a relatively straightforward and scaleable implementation. I will review the top-level mission concept, simulations and performance estimates, as well as the astrophysics and lunar science goals.