This morning crytek and EA Games released the open beta version of Crysis 3's multiplayer. At the moment the open beta only has two game modes and maps.  If you would like to be in the open beta you must download the origin client (Pretty much like steam). Once you've done that then go to the bottom of this article and press on one of the buttons.
"Hunter Mode:
This multiplayer game mode is all about survival of the fittest. There are two teams, initially comprised of two permanently cloaked “Hunters”, and up to fourteen CELL troopers awaiting extraction. Each trooper slain respawns on the Hunter team to prey on their former allies, building to a frenetic climax. If any of the troopers survive the round, the hunters lose. Whichever way you play, Hunter Mode delivers a heart-pounding test of strategy and survival."
"Crash Site Mode:
This multiplayer game mode is the ultimate King of the Hill type experience. An Alien dropship deploys a pod at random around the map. Players on each team must remain near the dropped pod in order to capture the zone and accumulate points. Each alien pod holds two shields players can utilize defensively as weapons. In addition, each Crash Site map will have a “Pinger”, a CEPH-constructed walking weapon of mass destruction. But be careful, other players can hijack the Pinger while you’re inside of it!"
"Beta Maps:
Museum - Roam the dark Ruins of Musem in downtown Manhattan and use the verticality to your advantage.
Airport - Close to the financial district, nature has taken over buildings and planes in this open fields area."
The beta started on January  29, 2013 (Today) and will end february 12, 2013. If you would like to join the open beta click the button below. We will be doing some previews and videos for crysis 3 so look out for these if your interested.