Resident Evil is less known for their light-gun arcade games as these are held in public places that are niche hang out spots. The Wii with its remote and Zapper attachment is just begging to be used as a light-gun and many of these games followed and Capcom jumped on the bandwagon. Umbrella Chronicles is one of the more solid light-gun games on Wii, but it must be played co-op or you're not going to have a good time.
The game has four chapters with each one following bits and pieces from Resident Evil 0, 1, and 3: Nemesis respectively with the final chapter being an exclusively unique section just for this game. Each chapter has three or four sub-chapters and a few side chapters that are shorter and feature an alternate perspective featuring Ada Wong, Albert Wesker, and one Umbrella operative Hunk. Story-wise, don't expect to get a comprehensive telling of the Resident Evil series as pre-rendered cut-scenes are chopped up and it's not very cohesive or easy to understand. This is more for people who played the older games before.
Outside of that the shooting itself is rather solid. There are over a dozen weapons in the game with your side pistol having unlimited ammo and various other guns like sub-machine, shotgun, rocket launchers, and hand-cannons making up the majority of the arsenal, but the ammo for these guns is extremely limited, and that's the first downfall of this game. Why make an action game from survival horror and keep the ammo count low? The pistol does very little damage and just forget about beating a boss with it. Ammo is incredibly scarce and requires you to have a partner as some scenarios and waves just can't be defeated with only the pistol. Hordes of enemies sometimes over a dozen will spawn in front of you and popping them with 8-10 shots each with a pistol is just not feasible. With a second player, it's possible, but solo is not. After chapter 3 I had to resort to a partner because it just gets too hard and too demanding for one player.
There are a good variety of enemies in the game with some not appearing until the final chapter, and the bosses are all unique and incredibly challenging and require great reflexes and aim and actual skill. Bosses are recycled from previous games, but fighting them in a 3D environment is pretty awesome. Some bosses have multiple stages, but these repeat in a cycle and can even include quick time events that require button presses or a quick waggle. Quick time events are peppered throughout the game, and thankfully not abused, but they don't appear on-screen long enough and the waggle ones won't trigger unless you start waggling the second it appears on the screen. This can lead to frustrating deaths.
Speaking of deaths, if you find a health spray this acts as an extra life and can resurrect you on the spot, but without one, you start at the last checkpoint. There are herbs lying around for health, ammo, grenades, and barrels just begging to be blown up to take out large groups. This is one of the most difficult light-gun games I have ever played, and sadly it's impossible to finish solo without having unlocked the infinite ammo. The first two chapters have a nice difficulty scale and it just ramps up way too hard on chapter 3 and 4. There's also an issue with the game feeling too repetitive and not having enough variety like vehicle scenes similar to other light-gun games. It relies too much on just shooting the same enemies ad nauseum.
Let's talk about production values. Capcom is never one to skimp on a Resident Evil game, usually, and while Umbrella Chronicles looks fine it shows it doesn't push the Wii in the right direction. It looks like a GameCube game at best with muddy low-resolution textures, but somehow there's still slowdown when too much is going on. It really could have looked better, even on the Wii as there are better-looking games on the system, but what's here is fine. The menus are pretty ugly with not much going on and everything looks so blurry and low-res. I need to redact my GameCube comparison from earlier, it's more like a Dreamcast port, to be honest.
Overall, Umbrella Chronicles is a decent light-gun game that requires a second player or you won't get very far. The boss fights are bombastic and fun and each is unique, but the same enemies repeat over and over and the scenarios don't change. You're just running down hallways or open areas blasting enemies. The game goes on way longer than it needs to with each chapter taking about 30-45 minutes to complete if you include the bonus missions. There is a lack in variety when it comes to other stuff to do to make this game just more exciting to play. The extras aren't worth unlocking as they require S ranks in each chapter, most of the time, and after finishing this game once there's no real reason to go back.