RESIDENT EVIL ZERO / Capcom / Gamecube
When a popular franchise begins, it usually has little bits of backstory lore in it that are there for world-building and are never meant to be fully fleshed-out ideas. For example, the first Resident Evil game opens by mentioning murders in the woods around Raccoon City and the disappearance of STARS Bravo team. Just little details to establish the story and the mood.
The people writing this aren't thinking that the franchise is going to take off and become one of gaming's biggest names. Once it does, there is increasing pressure/temptation to comb through all these little bits of dangling lore and develop them into their own properties (especially if it's Capcom we're talking about). This is usually a bad idea from a storytelling perspective because it's totally unnecessary, it doesn't match whatever players built up in their imagination, and it creates these epic retconned quests that are oddly unreferenced in the already-released games. But companies can't resist the sweet sweet song of those $$$, so these titles get foisted on us anyway.
Resident Evil Zero is one of those things. Released in 2002, the series was already becoming a bit long in the tooth and overstaying its welcome by the time this came out. Additionally, survival horror had evolved with titles like Eternal Darkness and Fatal Frame. While Zero gets experimental with controlling two characters at once, and it's definitely the best of the original RE games in terms of graphical detail and ambient sound, it insists on clunky antiquated gameplay and design paired with a totally unnecessary story that seemed to rub series fans the wrong way.
The game stars Rebecca Chambers, major supporting character in Chris's path of the original game. Of course, we know Rebecca survives this ordeal and makes it to the mansion where she mysteriously becomes far less competent all of a sudden. So, Billy is introduced to have a new player-character with an uncertain fate. Billy is an escaped convict and the initial reason STARS Bravo is out combing the woods, but focus quickly shifts as a passenger train is stopped and massacred by Singing Sephiroth and his merry band of evil leeches.
So, as the kids would say, lots to unpack here. An origin story about the T-virus initially escaping the lab isn't a terrible idea, I guess, but it seems better suited for a little web-based bonus thing than a full-length game. It also cuts off a lot of fun fan theories by establishing a canon, and in this case the canon is ... evil leeches somehow took over an incongruously bishy scientist who then controls them by singing opera? Must have been some good drugs going around the Capcom offices at the time.
So fan sentiment overwhelmingly seems to be that this is a weird and dumb origin story. Capcom was also confronted with the issue of having to create an epic hero's journey that ultimately doesn't matter, because it just leads to the start of Resident Evil. That leads to a lot of delicious padding and a game that feels stretched out by interminable backtracking.
Rebecca links up with Billy about 10 minutes into the game, as you explore the stopped train trying to figure out what caused all the carnage. The train turns out to be like the introductory tanker level of Metal Gear Solid 2; a more well-done but small segment that baits you into the game, only to switch you to a more boring and tedious backtracking-filled generic mansion/lab for most of the rest of its length.
I thought the character-switching actually had a lot of promise, but it just wasn't realized well. Series veterans can probably already see one major issue developing - the games often expect you to Tecmo Super Bowl your way around zombies to conserve precious ammo, and that's gonna be an issue with two characters to manage in real-time. Well, the game's answer to this dilemma is to just make most of it take place in narrow corridors for some reason, where you can't get around the enemies and instead have to just get really good at headshots to use as few bullets as possible.
This is made a little more manageable by a new inventory system, but that ends up having its own problems. Though save rooms are still present, the Magical Boxes that would transport items between them are now gone. Instead, items have permanence throughout the game world and can be dropped and retrieved from most screens. This one is kind of a mixed bag; between having two character inventories and being able to drop stuff off nearby, you can end up toting more weapons and ammo along ... but it also promotes even more backtracking, which the game was already too heavy on.
The character-switching is also very much a mixed bag. The two characters can separate and be on different screens, and you switch between them quickly with a tap of the X button. When on the same screen, you can move the other character simultaneously by using the little C-stick analog nub. Fortunately, the AI is very conservative with ammo and won't shoot at monsters until they're definitely in range and closing in, it also has a slow rate of fire and does a pretty good job of aiming for the head.
It mostly works out alright, but there are some crappy unexpected ambush segments where the characters are separated and can't pass items to each other. Sometimes one is expected to rescue the other from some peril, and if that one doesn't happen to have enough ammo or health items in their inventory you're pretty much just screwed.
The antiquated save system is what absolutely kills it, though. It's the same system of only saving in sporadic save rooms, and with a limited amount of ink ribbons to boot. In a game that expects you to play 30-60 minutes at a clip between save opportunities, and will also require you to skip at least a handful of those opportunities due to a lack of ribbons, this just isn't acceptable - especially for a grown-ass adult with a job and a life. Add in potential surprise no-win situations when the characters separate and you can't pass enough ammo to one, and it's unbearable. By 2002 Capcom should have had a better system in place than this.
* Gameplay Video