What is the Half Life Logo Spray for?

[Twist It And Go]

I've never played this game before and heard so many good things about it that I decided to give it a go, especially considering Portal 1 and 2 were so amazing. I'm just curious as to what the purpose of spraying the logo in the campaign is? Also, why can I only seem to spray it once every so often?

[Heinrich Butts (Proctologist)]

gordon freeman wuz here

[Twist It And Go]

lol ok. It was confusing because I had just started the game and hadn't even picked up any weapons at that point. So the only things I could do was move, jump, crouch, flashlight, and spray paint. Thought there might be something significant about it

[Roncon]

For science of course...

[1singur]

in SP you can actually use it to mark the "labyrinth" areas that you visited before (like the airducts that spread in multiple directions). tagging next to a door or an entrance warns you that you took that path previously.