Weapons
HVS.45 prototype pistol now avaible in multiplayer
ACR- Eclipse (allows you to go invisible, unlimited ammo, overheats)
Iron sights on mp5 and pistol
Turrets (auto/player control)
Re-designed Spas 12
Re-designed Scar
Re-designed TPC
Grenades leave red trail
Bullets leave yellow trail
Grenade space lowered
Phase rifle (allows you to look through wall and is radiation powerd)
Vortex cannon renamed to Aegis Device
TPC launcher canister bounce
TPC alt fire: promixity mines
Hive cannon alt fire: Honey Glob
Same crosshair for each weapon
Stronger weapons take up more weapon slots
2-3 grenades

Stages

Possible 15 stages with possible DLC
Two stages shown at E3: Lost City of Z, and a possible European city
Environmental hazards – e.g. Spaceship afterburners
Ladders – Interactive
Stages no longer mirrored
More live environments
Sniping spots – High ground spots
New alien encryption
Developments within Lost City of Z map

Online modes

96 friends, 96 rivals
Voice chat with rivals and friends
When rival added, it sends them a pop-up invite
Downloadable patches
Party system unlikely
Deeper character customization
Match voting system changed
12 players online
Single player and multiplayer profile is merged
Username bumped up to 12 characters
Username cannot be changed – permanent
Pick up coins in invasion mode
Invasion mode can be played single player
4 player online or offline for invasion mode
No bots in single player invasion
Hardcore modes
Other

Music is now darker
Diego Stocco is not returning
2 new character models (possible new species)
Four bosses
NPC’s present
AI communicate with one another
Interactive objects in environment (e.g. knocking over tables for cover)
AI can hold random weapons
AI behaviour varies depending on the weapon (e.g. enemies with shotgun will come up close. Enemies with a sniper rifle will stay in the back)
Redesigned lock on
In-game weapon load out customization
3-4 perks
Possible 15 maps (More with DLC)
Working closely with Nintendo to offer DLC
Voice chat with rivals and friends(similar to metriod prime hunter system)
Environmantal hazards – e.g.

Link