Oh no! The TARDIS is malfunctioning, and the citizens of Earth need your help. The Daleks are once again plotting to destroy the universe as we know it, and are planning to attack the time-space beacons (the large green circle) that are popping up from points in Earth's future. If the Daleks can successfully destroy one, the future Earth will die. Fortunately, the beacons are self-healing and, over time, will recover from damage. In the meantime, however, you must direct the TARDIS to rescue the beacons before the daleks destroy it! However, the TARDIS has lost its time-travel capabilities, so it can only move in spurts toward your mouse at a speed proportional to the distance away your mouse pointer is. Press "b" to receive a boost upward and get the hollow green circle to increase your boost fuel. Yes, the dalek gets faster over time.
Credit to Mr. Herzog.