Counter-Strike: Global Offensive is getting a free weekend, for all you holdouts who can't decide if you should stay or you should GO. It starts today, and lasts until Sunday at 1 PM PST. In case you're just dipping your toe in for the first time, Valve has issued a little primer to get you ready for the various headshots that will keep you from playing the game for any more than 15 seconds at a time.
The Counter-Strike blog recommends that newcomers start with the Weapons Course for the basics, and then try out the Arms Race mode, since it's the one that relies the least on knowing the maps or team strategy. More experienced hands might want to jump straight to Demolition Mode. And in general, Casual Mode might be the best choice for lapsed players or people who are just generally terrible at shooters.
If you still need a little more convincing to at least give it a try, check out our review.