Age of Wushu is still officially launching on February 1st, but its beta servers are remaining up and character data will not be wiped, making this more of an early access for subscribers. City of Steam is focusing on functional improvements to the game client prior to open beta, while Marvel Heroes has introduced a Founders Program for players to buy into the game early. And while WildStar is still not even in closed beta testing, you can get a sense of how the very limited alpha plays.
You want to know about more games in testing? Perhaps in list format past the break? Then you're in luck.