[Update 2] Lots of updates!
[Update] NIS America added to the entry list.
[Original] Listing out all of the games that will be at any E3, let alone E3 2015, is like chasing a moving target. Sometimes publishers and developers will discretely outline their lineup of games at the convention, and sometimes they don't. And even if they announce those games, they may have secret games under wraps that aren't a part of their official lineup… or games they are only showing to people behind closed doors… or games that may show up at the very last minute.
So this list of games in alphanumerical order is definitely preliminary, and any games we're mostly unsure about has been marked with a (?). There are still some titles that are under embargo, so I can't list them here, but suffice it to say, there are plenty more. If you think I've missed any, and I'm sure I have, let me know in the comments.
2K Games
Battleborn
XCOM 2
WWE 2K16
505 Games
Assetto Corsa
Abzu
Ember
ADR1FT
Payday 2: Crimewave Edition
Brothers: A Tale of Two Sons
Overkill's The Walking Dead
Activision
Call of Duty: Black Ops III
Destiny Expansion (?)
Guitar Hero Live
Skylanders SuperChargers
Atlus
Persona 5 (?)
Persona 4: Dancing All Night
Bandai Namco
Dark Souls III
RIDE
J-Stars Victory Vs+
Godzilla
One Piece: Pirate Warriors 3
Tekken 7 (?)
Naruto Shippuden: Narutimate Storm 4
Supernova
Saint Seiya: Soldiers' Soul (?)
Project X Zone 2 (?)
Bethesda
Battlecry
DOOM
Fallout 4
Capcom
Mega Man Legacy Collection
Resident Evil 0 HD
Devil May Cry 4 Special Edition
Street Fighter V
Deep Silver
Mighty No. 9
Risen 3: Titan Lords – Enhanced Edition
Homefront: The Revolution (?)
Dead Island 2
Electronic Arts
Madden NFL 16
FIFA 16
NHL 16
PGA Tour TItle (?)
Mirror's Edge 2
Star Wars: Battlefront
Mass Effect 4 (?)
Need for Speed
Focus Home Interactive
Space Hulk: Deathwing
Battlefleet Gothic: Armada
The Technomancer
Divinity: Original Sin – Enhanced Edition
Farming Simulator 15
Blood Bowl II
Mordheim: City of the Damned
Vampyr
Konami
Metal Gear Solid V: The Phantom Pain
PES 2016
Microsoft
Crackdown
Fable Legends
Forza 6
Gears of War Project
Halo 5: Guardians
Quantum Break (?)
Rise of the Tomb Raider
Scalebound
Natsume
Harvest Moon: Seeds of Memories
Ninja Strike
Gotcha Racing
Brave Tank Hero
NIS America
Disgaea 5: Alliance of Vengeance
Danganronpa Another Episode: Ultra Despair Girls
Rodea the Sky Soldier
Nintendo
Mario Maker
Chibi-Robo!: Zip Lash w/ Chibi-Robo amiibo
Dr. Mario: Miracle Cure
Bravely Second End Layer
Pokemon Super Mystery Dungeon
LBX: Little Battlers eXperience
Puzzle & Dragons Z + Puzzle & Dragons Super Mario Bros. Edition
Splatoon
Art Academy: Home Studio
Project Treasure
Mario & Sonic at the Rio 2016 Olympic Games
Xenoblade Chronicles X
Yoshi's Wooly World
Star Fox Wii U
Square Enix
Deus Ex: Mankind Divided
Dragon Quest Heroes
Final Fantasy XIV Online: Heavensward
Hitman Sniper
Just Cause 3
Life Is Strange
Kingdom Hearts III (?)
Final Fantasy XV (?)
Sony
Ratchet & Clank
Amplitude HD (Harmonix)
God of War III HD
Thumper
Uncharted 4: A Thief's End
Until Dawn
Uncharted: The Nathan Drake Collection (?)
Tearaway Unfolded
Everybody's Gone to the Rapture (?)
No Man's Sky
Alone With You (Benjamin Rivers)
Capsule Force (Klobit/Iron Galaxy)
Chasm (Discord Games)
Crossing Souls (Fourattic/Devolver)
Cosmic Star Heroine (Zeboyd Games)
Death Tales (Nine Tales Digital)
Drawn to Death
Dungeon Defenders 2
EarthNight
Enter the Gungeon
Fat Princess Adventures
FutureGrind
Galak-z: The Dimensional
Gang Beasts
Gnog
Guns Up!
Journey
Kill Strain
N++
PlanetSide 2
Relativity (Willy Chyr)
Rocket League (Psyonix)
Salt and Sactuary (Ska)
Skullgirls: 2nd Encore (Autumn)
Snow (Poppermot)
Soma (Frictional Games)
Super Meat Boy (Team Meat)
Super TIme FOrce Ultra (Capy)
The Banner Saga (Vs. Evil)
The Tomorrow Children (Q Games)
The Vanishing of Ethan Carter
Drool (Thumper)
To Leave (Freaky Creations)
Ubisoft
Assassin's Creed Syndicate
Tom Clancy's The Division
Tom Clancy's Rainbow Six Siege
Versus Evil
Afro Samurai 2: Revenge of Kuma, Volume 1
Armikrog
The Banner Saga 2
Guild of Dungeoneering
Kyn
Skyshine's Bedlam
XSEED
The Legend of Heroes: Trails of Cold Steel
Earth Defense Force 4.1: The Shadow of New Despair
Senran Kagura Estival Versus
Return to PopoloCrois: A Story of Seasons Fairytale
Senran Kagura 2: Deep Crimson
Onechanbara Z2: Chaos
Corpse Party: Blood Drive
Earth Defense Force 2: Invaders From Planet Space
Warner Bros.
Batman: Arkham Knight
LEGO Dimensions
LEGO Jurassic World
Mad Max
Other
Wizards of the Coast – Sword Coast Legends, Magic Duels: Online, Enter The Dungeon
Bossa Studios – I am Bread, Surgeon Simulator
Clever Plays – Leap of Fate
Devolver Digital – Broforce
Harmonix – Rock Band 4
Disney – Disney Infinity 3.0
Epic Games – Fortnite
Seasun Games – Relics of Gods
Telltale Games – The Walking Dead, Game of Thrones, Tales from the Borderlands
Alonso Martin – Heath Forth, Alicia
Ruffian Games – Hollowpoint
Vlambeer – Nuclear Throne
CI Games – Sniper: Ghost Warrior 3
