Honestly, I had much more fun with this than I rightly should. This is little more than a collection of cut-scenes from a Resident Evil game that was unfortunately never made.
The animated versions of the franchise have always been more entertaining than their the 'real-life' counterparts anyway, and this is as good an example as any of those that explains what Leon, Claire, Chris and Jill did next.
Here, they are drawn to Alcatraz to investigate a new version of the T-virus that can be delivered without being bitten and causes the victim to kill indiscriminately like always, but the people that are bitten do not turn into zombies themselves.
There is a reason for this of course and the antagonist and creator of this new deadly strain has their own reasons for wanting to end the world as we know it, even if that reason is a little thin, plot-wise. It's a little easier to overlook the obvious continuity errors and nonsensical scenes, given that you're already enjoying the premise and the farcical scripting and voice-acting.
Was I entertained? Most certainly. And you don't really need to know an awful lot of what has gone on before as little reference is made to previous events. Additionally, this is a new nemesis so the absence of the Umbrella Corporation or Albert Wesker makes little to no difference.
Overall, a very pleasing visit to our favourite Resident Evil characters kicking ass all over again.