Counter Strike: Global Offensive is free on Steam this weekend.
Now, I know what you're thinking.
"Oh I've played since 1.6"
"Just a redone CS:S why bother"
Let me try to convince you otherwise.
They polished up EVERYTHING.
To include one of two concerns I have ever had with CS:S...
The hitboxes.
Which makes the game a bit more fun, since the bullets you're shooting might actually hit where you intend.