Anyway. Since 2008.
Dead Nation, Dead Block, Dead Space, Dead Space 2, Dead Rising 2, Left4Dead, Left4Dead 2, Call of Duty: World at War: Zombies, Yakuza: Dead Souls, Rock of the Dead, Zombie Panic in Wonderland, Zombie Wranglers, Undead Knights, The Zombie Island of Dr. Ned, Zombie Tycoon, Burn Zombie Burn!, Plants vs. Zombies, Zombie Apocalypse, I Made a Game with Zombies in It!, Shellshock 2: Blood Trails, The Last Guy, Little Red Riding Hood's Zombie BBQ, Teenage Zombies: Invasion of the Alien Brain Thingys!, Killing Floor, OneeChanbara Revolution, Resident Evil 5, Resident Evil: The Darkside Chronicles, Resident Evil: The Mercenaries 3D, Resident Evil: Revelations, Resident Evil: Operation Raccoon City, Resident Evil 4 HD, Resident Evil Code: Veronica X, The House of the Dead 2 & 3 Return, The House of the Dead: Overkill, Silent Hill Homecoming, Silent Hill: Shattered Memories, Silent Hill: Downpour.
From one list I found online, anyway. I recognise well over half of those titles.