Good news for Lumia WP7.5 device owners. Facebook Beta with all features available for the WP8 devices, has been updated to be compatible with WP7.5 devices. It is now available at WP store and can be installed from the below link.
Free version of Halo: Spartan Assault has come to store as well. It is named as Halo: SA Lite and one of the mission seems to be available for free. Install the game from below link.