For example, instead of the lunar rendezvous method that NASA chose for the Apollo program, the player can opt for Earth-orbit rendezvous or even direct-ascent where a single giant spacecraft lifts off from Earth and lands on the Moon.
The watch was used to time the duration of the Descent Orbit Insertion maneuver and to time the rendezvous maneuvers after launch from the lunar surface.
The timer could also be used with the rendezvous back-up charts to ensure the LM could join the CSM in lunar orbit after the crew launched from the lunar surface.