Diehard fans will be pleased with this, but you can't shake the feeling it's out to take your money and little else.
Now as any fan of the series knows, Rebecca appears in that game traumatised but making no mention of the events in this one. It's this casual attitude of Capcom's that adds a lot of backstory but leaves plot holes so substantial you need to be a nuclear scientist to connect the dots convincingly, as they merrily retcon the story without much thought for continuity.
The series once again introduces a new character in Billy Coen, a U.S. Marine convicted of the slaughter of innocent people in an African village. Whilst being transported by Military Police, they are attacked by the Cerberus dogs and he escapes. The Bravo Team splits up to look around, and Rebecca finds a stopped train and enters, which is where the game begins.
Immediately she is attacked by zombies and fends them off in a panic. She is soon joined by Billy who assists her, and the two form an uneasy partnership to help eachother. This is where the gameplay becomes interesting: while not strictly a two-player game, it requires cooperation. You can switch between Rebecca and Billy to overcome obstacles at various points. For example one character may find their path blocked, but you can take the other and find an alternative solution that frees your partner. You can also swap items and ammo which is a handy way of keeping weapons and healing equipment stockpiled.
Billy and Rebecca battle their way through the train, taking on monstrous bosses along the way, ending up at the old Umbrella Training Facility. Abandoned for years, intelligence picked up informs us of Umbrella's origins and that of the T-Virus, engineered in part by Dr. James Marcus, one of Umbrella's founders and as with most antagonists in Resident Evil games, utterly unhinged and immoral. It's soon revealed that his likeness is causing all the carnage.
The game by and large sticks to standard Resident Evil fare: lots of mutated animals as enemies including apes and bats, zombies galore and some very cool prototypes including the iconic Tyrant. Combat remains the same as in previous games: run, stand still, aim, and shoot, and the backgrounds again are pre-rendered yet owing to the improved graphics power of the Gamecube, very detailed and macabre.
The issues with the game are the fact Capcom hadn't really tried anything especially new. Gameplay is pretty much the same regardless of the fact you can control two characters: essentially it's window dressing for what was becoming stale. Shortly after, Resident Evil 4 was released, again on the Gamecube, and wiped the floor with this (and just about everything else), which only compounds the shortcomings of this game.
This caters for the hardcore fans who stubbornly resisted the impending change to the Resident Evil formula as we now know it. The gameplay and combat is solid and the story, whilst taking some unbelievable liberties, is actually quite well thought out.
The negatives are the repetitive gameplay and brazen attitude of Capcom to dish out yet another rehash of the same idea, something they tend to do with all their popular products such as StreetFighter and Mega Man. It's this cash-cow attitude to the fans that feels like a cheap way to get more money out of you without actually offering anything that new. It's enjoyable sure, but we've come to expect better.