Sentinel

In 2155, through a multi-dimensional portal, an alien invasion annihilates nearly the entire human race. Some of the people who manage to survive are miners hidden on the dark side of the moon. Years after the invasion, and with the use of new technology, three soldiers are sent back to Earth. Their plan is to connect with the human resistance and end the occupation of the aliens. Upon arrival, our three heroes soon find themselves face to face with the all-powerful guardian of the portal known as the Sentinel and its army. Despite being completely outnumbered, the soldiers are determined to accomplish their mission at any cost and reclaim Earth.