As we await Resident Evil 5, there's just enough time to take you through the viruses, monsters and mutations that are the true stars of this amazing survival horror saga. Join us as we link and untangle the most knotty of gaming's histories. Bring some scissors.

Resident Evil 0

Released in 2003 (and so after RE 1, 2, 3 and Code Veronica ) this chartered the events leading up to the Spencer Mansion incident, as the S.T.A.R.S. Bravo Team are sent to explore the Arklay Mountains where a series of grisly murders have taken place. The team is attacked by zombies, but rookie Rebecca Chambers is split from her colleagues and teams up with escaped military convict Billy Coen in order to escape to safety. This involves battling a leech monster that often takes the form of murdered Umbrella scientist Dr. James Marcus.

Links in the chain

James Marcus developed the T-virus by combining the mutagenic Progenitor Virus with leech DNA. He was then brutally murdered by Dr. William Birkin and Albert Wesker on the orders of Umbrella President Ozwell Spencer.