The non-certificated pilot departed from the airport in the unregistered experimental gyroplane for a local area flight. Shortly after departure, the experimental 2-stroke engine sustained a total loss of engine power. The pilot initiated an autorotation to a swamp. After successfully landing the gyroplane, the pilot began the shutdown process. However, due to the “spongy and soft” ground, the gyroplane began to “wobble,” and the gyroplane rolled over to the right. The pilot was then pinned under the gyroplane, and he was unable to release the lap belt. About an hour later, he found his cellular phone and contacted first responders who were able to later extract him from the gyroplane. The single seat gyroplane, with no airframe serial number, sustained substantial damage to the main rotor system and the empennage. Postaccident examination revealed that the gyroplane had an empty weight of about 405 pounds, that exceeded the 254-pound empty weight limit for powered ultralight vehicles. The pilot reported the gyroplane held “5 to 6 gallons” of fuel, as powered ultralight vehicles are not to exceed a 5-gallon fuel capacity per regulation. When the pilot purchased the gyroplane several months prior to the accident, it came with no documentation, and thus the maintenance history for the airframe and the engine was undetermined. The engine manufacturer has previously published a warning that states, “This engine, by its design, is subject to sudden stoppage.” As a lesson learned, the pilot suggested to have a cutting device available if an occupant is unable to activate the release mechanism for a restraint system.