Significantly, each playable character has unique attributes, and so you're nudged into taking on specific roles such as medic or armourer. There are also new utility items, including a tool kit that can be used to break into storage rooms. The range of weaponry is significantly broader than before, and guns can now be customised with sights, stocks and so on. These can be countered, to some extent, by booster cards which might give you extra ammunition, more health or other advantages.

Corruption cards, dealt by the AI director, might cause the environment to be enveloped in dense fog or increase the number of enemies. Decks of cards come into play, smartly altering the way each game plays out. The intervening years have forced some small but important changes to the format. Yet again, you must team up with three other players (known as 'cleaners') and take on the undead, scrambling across town from one safe room to the next. Back 4 Blood, as its title strongly suggests, is Left 4 Dead 3 in all but name. Now, free of Valve's notoriously sketchy release schedule, original developer Turtle Rock Studios has finally unleashed a spiritual successor to its genre-defining masterpiece. One year later – to the day – they released a sequel. In 2008, legendary games publisher Valve released Left 4 Dead, a hugely influential multiplayer survival game which pitted a group of four humans against a horde of 'infected' (basically zombies, back when that word was unfairly maligned). The spiritual successor to Left 4 Dead is thrilling and stressful

Left 4 dead