Project Apollo - NASSP (also known as NASSP or NCPP) is an add-on for the Orbiter space flight simulator. Project Apollo simulates the Apollo missions to Earth orbit and the Moon, and is slowly expanding to simulate planned post-Apollo missions that never flew.
Emulation of the onboard Apollo guidance computers, along with some ancillary items needed to make the emulation do something interesting. "AGC" stands for Apollo Guidance Computer. The AGC was the principal onboard computer for NASA's Apollo missions, including all of the lunar landings. Both the Command Module (CM) and the Lunar Module (LM) had AGCs, so two AGCs were used on most of the Apollo missions, but with differing software. The computer and its software were developed at MIT's Instrumentation Laboratory, also known as Draper Labs.