In Atari 2600 Sentinel, the player controls a scientist piloting the Sentinel, a glowing orb they invented that can absorb and store energy. Earth is invaded by aliens, and the scientist uses the Sentinel to travel to four alien planets – Alptaurus, Ceruptus, Vulnavium, and Asceptron – with the objective of destroying their power stations, which are guarded by alien lords.
The gameplay involves navigating the various landscapes of the alien planets, battling the alien lords, and destroying their power stations. Players must also manage the Sentinel’s energy, which is crucial for its survival and offensive capabilities.
After successfully destroying the power stations on all four planets, the player encounters the entity that controlled the alien lords. The final challenge is to defeat this entity and save Earth from the alien invasion. Sentinel offers a captivating sci-fi adventure that combines action, strategy, and exploration, challenging players to save humanity from a powerful extraterrestrial threat.