A half-life refers to the time spent coming down from a drug. What does this have to do Gordan Freeman and Aliens?
Why is this the name for the series?
Kyreo is right, the "half-life" is the time it takes for any substance to decay and reduce amount/quantity by half. It was most popularly used (Before the game series), to refer to radioactive decay, but is an acceptable term for anything that has a set-rate decay.
The more you know!
"Half-life" is a scientific term, referring to the amount of time it takes for something to decay into half of what it originally was. Blue Shift, Opposing Force, and Decay are all also scientific terms that fit within the theme of the game. It has nothing to do with drugs.
This edit will also create new pages on Giant Bomb for:Beware, you are proposing to add brand new pages to the wiki along with your edits. Make sure this is what you intended. This will likely increase the time it takes for your changes to go live.