StarCraft II: Heart of the Swarm doesn't officially go live until tonight at midnight Pacific time, but if you've got the new StarCraft II expansion installed already, you can play it right now.
To prepare for the launch, Blizzard has disabled Global Play, the feature that lets you switch between servers on the online network Battle.net. But as discovered by NeoGAF user Mr Cola, you can re-enable the service and switch to the Southeast Asia region, where the game is already live right now.
Here's what to do:
1. Create a notepad file and save it as regions.xml. Add the following text:
(Our site's text editor won't let us make the code copy-paste-friendly, so if you want to cut and paste it, head to the GAF post and take it from there.)
2. Save the file to your StarCraft II installation folder—the same folder where the game's .exe file is.
3. Load up the game and don't log in. If your account is already logged in, just click the arrow next to your account name so you back up a bit. You should see a "Regions" tab on the left side of your screen.
4. Switch the region to Southeast Asia. Make a new account.
And...
Bam, now you can play Heart of the Swarm. Be warned: your single-player progress may will not carry over if you go back to another server in the future. But you should be able to play the whole game on the Southeast Asia region. Enjoy!