Stephen Hawking was an atheist, and believed that "the universe is governed by the laws of science". He stated: "There is a fundamental difference between religion, which is based on authority, [and] science, which is based on observation and reason. Science will win because it works." In an interview published in The Guardian, Hawking regarded "the brain as a computer which will stop working when its components fail", and the concept of an afterlife as a "fairy story for people afraid of the dark". Can anyone remember what life was like before they were born? I think not.

My research team and I perform an experiment that inadvertently creates an inter dimensional rift in spacetime. Intelligent (and confused) alien lifeforms from the Xen dimension come pouring through multiple breaches inside the Black Mesa facility, attacking anyone in sight. As scientific, military and civilian personnel fall under the alien onslaught, I find myself targeted not only by the alien monsters, but also the Hazardous Environment Combat Unit (HECU), a U.S. Marine Corps military force sent to contain the situation.