Dota 2 has dropped queuing to sign-up, and can now be accessed by all. According to Valve, an upgrade in server tech has made it the right time to take the wraps off the popular MOBA.
Even with the controlled level of access, 6.5 million active monthly members have been playing, according to a post on the Dota blog. Though sign-ups aren't required, if you have a friend who's playing, you both can get bonuses by having them refer to you. Alternately, you could just visit the Steam page and click on "Play Game."