Zynga today reveals its very own social game platform, Zynga.com, which was previously called Z-Live and Zynga Direct. The service launches today with five of Zynga’s best-performing games: CastleVille, CityVille, Words with Friends, Hidden Chronicles and Zynga Poker.

Here’s what Zynga.com is: a platform on which social games can run synchronously and relatively seamlessly between it and Facebook. A CityVille player logging into Zynga.com today will find their city exactly as it appears on the Facebook canvas, with the same amount of virtual goods in their inventory and same amount of virtual currency in their e-wallet. Thanks to a deeper-than-anything-we’ve-seen integration with Facebook Connect, all in-game activity that takes place on one platform happens on the other. That CityVille player can buy a new park decoration on Zynga.com and it will appear in Facebook if they player were to jump back to the social network and play CityVille there. A Facebook player can used Credits to buy 20 Crowns in CastleVille and those 20 Crowns will be in the virtual bank if the player jumps to Zynga.com.

Here’s what Zynga.com is not: an alternative to Facebook. The service is focused on the games experience to the exclusion of almost all other social networking tools. Players can’t post pictures, can’t create events and can only group themselves by Facebook friends and players that play the same games. The only social network features Zynga.com cribbed from Facebook are the chat function, social discovery of new friend connections and a live app ticker for games activity (which is something Facebook recently disabled on canvas apps).

Read the rest on our sister site, Inside Social Games.