There is actually no fixed release date for this project. It's done when it's done.

Gameplay
interactivity! introducing the function "grab" as "use" displayed as a hand symbol ingame.
buttons, switches and consoles are only triggerable with the new "use" key
dead human bodies can be looted for random ammunition and inventory items
killing enemies gives the player random drops like flares, health and ammo
pre-placed items like flares, health and ammo are rare and have a random chance to appear
enemies will spawn in their area but at different places
the quadshot is now an official weapon and can be found in the singleplayer campaign.
more interaction with the native Nali species
Level Design
outdoor levels will have two versions ( sunshine and raining, randomly choosen )
increased amount of details on level geometry for each map
immersive atmosphere by using Unreal 227 based effects
interesting new changes in trigger mechanics
more secrets and new places to explore
several bug fixes and adding new bugs
detailed new skybox which fits in to the level seamlessly
New Effects
the suns of NaPali will now dazzle the player
2D fire sheets are now replaces by fire emitters
new enemy projectile effects
new stunning player weapon effects
new explosion effects
footstep sounds based on the ground material