By far, the best extra game mode throughout the Resident Evil series has to be Mercenaries. While it debuted in the classic RE3, its incarnation in RE4 completely transformed the side game. Giving you an arena to kill as many enemies as possible while making sure to keep the combo counter alive made it arguably more fun than the campaign.
When booting up RE4, 5, or 6, some people would just play Mercenaries mode. It's that enjoyable. While the various Mercenaries modes have plenty of awesome characters to choose from, you also need some sweet maps to tear through. Most of them are very unique, with different layouts and assortments of enemies.
10 Castle: Resident Evil 4 Remake
The Castle was a pretty brutal map in the original RE4. With its tanky zealots, hard-to-hit Garradors, and pin-point accurate archers, it's arguably the toughest to achieve five stars in. The remake's edition of the map, though, is nicely streamlined. It's not as big, but what's there is more compact.
The open environment makes killing enemies more enthralling this time around. Plus, you actually get to use the cannon, which is a definite step up over the original. Blasting zealots with cannonballs is a lot of fun and feels like something you would see in RE5 or 6.
9 Village: Resident Evil 4 Classic
Resident Evil 4 remake's Village had a lot of differences from the original. The back end of the house on the right has a new window entrance, and the barn to the very left is accessible. However, these two elements were in the original game's Village but in Mercenaries mode. The Village here was redesigned to fit the pure action-focused gameplay of Mercs.
It worked great, and the Chainsaw Sisters were a legitimate threat since you don't have Mayhem mode, like in the remake. The map's got a nice little safe zone in the left barn, where you can shoot enemies while kicking the ladder down. This is great for beginners, and the stage is a solid introduction. It's easy to see why the remake borrowed a lot of the layout for its Village.
8 Waterworld: Resident Evil 4 Classic
Waterworld has to be the most iconic Mercenaries map in the original Resident Evil 4. Its design is unique, with plenty of verticality, but one aspect above all else makes this map notable. Once you encounter Super Salvador or his official name, Giant Chainsaw Man, you know stuff's about to go down. He puts a total stop to your activity as you must deal with this deadly boss.
His main attack is swinging his one-hit kill chainsaw at tremendous speeds. He's also flinch-resistant unless you aim for the head, which is hard to do when he moves so quickly. You're constantly on the run here to stay alive, and the fact that he only appears in this mode makes it even more striking. The boss alone makes this map hectic, but that's why it's so fun.
7 Public Assembly: Resident Evil 5
The first Mercenaries map in Resident Evil 5 is Public Assembly, and it's a great start. A remixed layout to the first big combat section in the campaign, it's a bit more complex than the previous introduction map Village. There's the core battle area and an area to the left that leads to a nice high-ground advantage in the main one.
Its design makes it great for playing Mercenaries cooperatively. RE5 introduced co-op to the mode, and there's just something about how these maps were designed that makes co-op the most fun in this game. RE6's maps seemed more geared toward solo play and PvP than co-op.
6 Village: Resident Evil 5
With the same name but totally different, Village has some nice gimmicks that make it a stand-out map. The main one is the spike traps. There are two areas you can push a button to raise spikes, and that will kill anything in its path. It's really satisfying because it can be quite hard to time. It feels even better when you hit other human players in Versus with it.
Once again, this map plays phenomenally in co-op as there are two halves to it. The left side is the Village, while the right side is the high-ground balcony. This allows both players to come together naturally after the beginning moments.
5 Experimental Facility: Resident Evil 5
One of the more pure fun maps in RE5 is Experimental Facility. Its entire design is vertical, with you either starting at the top or bottom and must make your way to the other side. The monsters here are the most deadly so far, with having the highest level Majini, the Base variants, and a battalion of Lickers. Depending on which version of Mercenaries you play, the Lickers will appear on mass later on or will already be there.
Either way, it's a tough map. Besides its hectic quality, this map is so fun because of the exploding Majini. Some, when killed, will violently explode, hurting everything surrounding it. This includes you and other enemies. This explosion can rack up the combo meter fast, making Experimental Facility one of the more enjoyable maps in No Mercy mode.
4 Ship Deck: Resident Evil 5
This map is massive but so well-designed. Ship Deck is similar to the first part of Chapter 6-1 in the main game but with a lot of shortcuts. The use of ziplines is incredibly helpful here, allowing you to quickly proceed to the other side of the map. Due to its verticality, sniping from up-high is a viable strategy in both Mercs and Versus.
Chainsaw Majini's come in pairs, and they're deadly, especially because they often come back from the ground and go berserk. This is one map you definitely want to stay together in co-op, as things can turn south fast. It's such an engaging stage to play, no matter the game mode, and you'll always have a blast.
3 Urban Chaos: Resident Evil 6
Out of all the starter maps in the Mercenaries, Urban Chaos is the best one. It's simple, with a big road, a line of shops at both ends, and a railway that splits the middle. However, its simplicity is what makes it work.
The excellent gunplay of RE6 shines in a level like this, and it perfectly jives with the gameplay loop of the mode. Plus, the simplicity works great as a starter map, too. The attention to detail is also nice, with the cool arcade showing off plenty of Capcom games.
2 Steel Beast: Resident Evil 6
Steel Beast is a little more complex than Urban Chaos. From an overhead view, the map would seem completely straight, but it offers a lot of verticality. The compact design makes it a bit more hectic when first learning the map, but when you're more familiar, it becomes all the more satisfying to play well.
Steel Beast actually plays great in co-op, which isn't a thing that can be said about every map in RE6. It's also a nice touch that the combo bonuses are something you have to shoot at and often far away. This encourages exploration when first starting.
1 Creature Workshop: Resident Evil 6
The final map in RE6 is huge and offers stiff opposition. You'll fight hordes of Neo Umbrella J'avo and many of its mutations, plus Napads as bosses. It's another vertical stage, but very fun to traverse through, killing enemies in your path to get all the time bonuses. You're constantly moving, as there's not one good area to stay in to rack up kills. This keeps the map engaging the whole time.
Creature Workshop is great to play in Solo and PvP, but the only grip is that it ain't the best in co-op or No Mercy. The sheer amount of enemies and cooperation play don't mesh well with the level design and its skinny walkways. However, in other modes, it's one of the most enjoyable maps to play.