Reality Checker is a timer that prompts the user, at user definable times, to do a reality check during the day to be used to help generate lucid dreams at night. It can also be used to help stay mindful for mediators. The user can also set if the program beeps when the timer trigger,s How many times the program beeps/flashes before it resets, And if the program windows will come to the front of all other windows when it triggers.
There are a number of web sites that explain what a lucid dream is and how to have one, just Google lucid dreaming. One of the main methods is to do regular reality checks during the day a reality check is checking to see if you are dreaming or not eg check if time is moving in a linear manner (which it dosent do during a dream.