Outbreak games are still my favorite. Something about normal every day folks survivng the outbreak is way more interesting. Probably why RE2 ranks just under them for me.
Yeah, I was thinking maybe some kind of third person version of Contagion, in that game you're in a police station, zombies are deadly, ammo is scarce and a team of up to 8 players is tasked with progressing through a level, fighting through zombies while completing various mission objectives in a linear order with the ultimate goal of escaping the map.
Something like that, with a ticking clock element, some metropolitan areas, a bit of variety with enemies like the occasional Licker or Hunter that's not just a bullet sponge but something you don't stand much hope of killing and have evade or outsmart. It doesn't have to be an epic story of a person overcoming a secret Umbrella espionage plot but something more grounded.
Four people have barricaded themselves in a police station, they discover they're infected or might be infected, they hear on the police radio that a helicopter carrying a couple of T-virus cures has gone down across town or maybe that the Umbrella team sent to retrieve some potential vaccines from an Umbrella owned private lab has been killed and the team decides to cross town to retrieve it. Hell, make the route either up to the players choice or variable depending on certain triggers.
If you're quick, smart and a bit lucky you can avoid the zombies in the police precinct, sneak past the Lickers that are crawling up the walls of the hospital, lead the Tyrant into an industrial hydraulic press in the factory, argue over who needs the three viable vaccines when there are four of you and then fuel up the old diesel train in the engine sheds to ride it out of town before it's either locked down entirely or suffers a 'gas leak' and goes up in a nuclear fireball.
I know it sounds a little, or a lot, like Left4Dead but I'm picturing a slower game, one where it's less hectic and much more creepy and atmospheric. In Left4Dead a horde of zombies is just an obstacle to fight through and tank is just two minute distraction, in my perfect Resident Evil game a horde of zombies is almost certainly death and the Tyrant is something that is as unstoppable and intimidating as The Terminator.