A game based around the premise of the 28 days/weeks later movies.
Just hear me out.
*You have an accurate depiction of London and surrounding areas. It can be done, and it has been done before(True Crime's L.A & Spider Man 2's New York). An open world environment mind you.
*The goal is to survive for, like, 28 days aprox. Just make it through the 28 days fending infected attacks and possible encounters with the military. Your health drops if you don't take care of it by eating bars or crashing somewhere to rest, and you need to keep moving to gather resources, and after a while, you can try and hole yourself in one place to see if you can withstand an infected raid, but that's not mandatory. In the long haul, run-ins with the infected are guaranteed.
*Have an accurately depicted backpack that can hold your stuff.
*collect melee and firing weapons for actual fighting.
*You can make barricades to hole yourself in one place to fend off the infected(just move stuff around a la Half-Life) if you are forced to. Things actually carry weight(again, ala Half-Life 2).
*Randomly scattered resources littered around the city. Things would be where they should (meds in hospitals, health items in malls, etc.) but in randomized quantities so you don't just hole yourself in one place all the time.
*Features driving segments but they are nnot overdone.
*Roaming packs of Infected that come out at night and wander the city, though many come out at day if you piss them off by catching their attention.
*Add co-op.
With enough random factors thrown around, like initial starting point, item placement, infected placement, soldier placement, vehicle placement, amount of gas in the tank for vehicles, etc. and since your actual goal is just to make it through 28 days aprox, it could be played indefinitely.
Basically, think of GTA IV with lots of tweaks but no added complexity in technology.
It could work as a perfect "party" game, also.
