The Virtual AGS is an emulation of the Lunar Module Abort Guidance System similar to the Virtual AGC. The AGS was a backup to the main guidance computer in the event that it was unable to abort a landing in an emergency.
Currently the Virtual AGS software is linked into the Project Apollo code, but isn't wired up to be operational. At some point in the future it should be fully supported.
- Apollo experience report: guidance and control systems Lunar module abort guidance system
- Virtual AGC and AGS Home Page