The English version of Half-Life 2 is called: half-life.

In the game, it is generally called hλlf-life, λ replaces a in the publishing name, and λ is a Greek letter, which represents the decay constant. The formal translation of half-life should be called half-life, but the pirates' translation skills at that time were limited, so they directly translated it as half-life.

So half-life should be called half-life. With this understanding, you can know the meaning of λ instead of a. The game is also full of nuclear radiation, so you can understand the meaning of λ. In Half-Life 1, the game’s trademark was given a large lambda in a circle at the very beginning. The most famous logo of the game is of course lambda, and it is probably the logo of the entire Black Mesa base in Half-Life 1. λ.

So in continuation, λ has become the most representative symbol of the Half-Life game. Although it may not have much to do with the plot, Half-Life 2 still uses this λ, which is a bit of an easter egg. Meaning. If you see the lambda symbol on the wall in the game, it generally means there are hidden resources nearby. You can search for them to get ammunition and medical kits. And the lambda mark on the civilian army you mentioned is probably just a small easter egg, indicating that these people are on the righteous side of the Half-Life game players.