I was thinking about beat-em-up games a bit.
Classic-style beat-em-ups are rare these days, limited to only retro games like Scott Pilgrim's beat-em-up or Castle Crashers. Castle Crashers is also arguable due to some unusually shoot-em-uppy mechanics. Speaking of which, there are still some shoot-em-ups, but that's a different genre. Not talking about Alien Hominid, here. Talkin' bout Streets of Rage.
By and large, classic beat-em-ups have been disbanded in favor of new mass melee combat systems. This is largely as a result of moving to 3D, where the beat-em-up is quite difficult to do properly. So designers adapted.
A few decided to dumb down the distance control and amp up the timing control, because navigation and NPC movement in 3D space was always a little bit less transparent and predictable. The big example of this is God Hand: distance control is still important, but it's clear that the big focus of the game is on timing. Timing your chains so that your disengage lets you avoid the next enemy. Deciding whether to knock back, combo, stun, taunt... it's all about controlling or responding to the rate at which the various enemies will approach you. It worked well, but its not a genre because nobody else ever did it again. Because people are stupid. But I would call it a "timing fighter" if it did have a genre.
Most 3D combat games drifted towards ranged attacks, because the camera is good at looking in the same general direction as the PC. So there were an abundance of shooters, yes, but also a growing abundance of "ranged melee" games, or as I call them, "crowd control" games. Some people would call them "spectacle fighters" - I dunno, I almost think that should be reserved for games where you mostly press X to tear off an enemy's head with a fifteen-second animation. Either way, in these games you're a "melee" fighter, but your "melee" weapons reach ten, fifteen feet. The idea is to keep the enemies under control while you whittle down their health. Examples: every 3rd person brawler you've ever played. Devil May Cry, Prince of Persia, God of War...
Again, because navigation in those games isn't as crisp and it's harder to remain aware of where all the enemies are, the developers decided to focus on a different aspect. The timing fighter largely ditched distance control in favor of timing, but the crowd control fighter doubled down on distance control and simply gave it a different mechanic so that it was less about movement.
However, these two methods are not the only options. As 3D marched on, our control over both the camera and the enemies grew. Now we have a new breed: the New Era Brawler, or what I would more explicitly call a "chain brawler".
The sterling example of this is the recent Batman games, such as Arkham City.
The core of these games is the idea that you CAN see all the enemies you're fighting. Even though it's 3D, there's never going to be anyone attacking from "off screen" unless something's gone very wrong. This means that the core problem with 3D brawlers - the limited camera - is largely waived.
Unfortunately, you can't easily go back to the original brawler mechanics, because they were all about understanding attack vectors. In 3D space, attack vectors are a lot more complicated due to the concept of "heading". Enemies are no longer simply facing left or right, but are now facing any which way they please, which makes it difficult to really slip them well. The "up-down" part of the brawler navigation is gone, and in its place is a very complicated second horizontal axis. So you can't just use the original brawler mechanics.
Instead, they focus on timing, similar to God Hand. But God Hand had a close camera and featured very precise and delicate close combat based around it. The long camera we use to get all our enemies on the screen makes it difficult to read the timing of individual enemies. So, um... PUT A GIANT BLINKING THING OVER THEIR HEAD!
Obviously, the giant blinking thing makes each individual enemy a lot simpler to time against. So instead of doing much fighting against single enemies, you tangle with a single enemy only briefly. They are like lego pieces and the combat is made of many of them, rather than each enemy being a challenge on its own.
Hence the name "chain fighter".
Anyone who's played Arkham City knows how these fighters play out: your position does't really matter much at all. In fact, your movement only matters in that it allows you to attack a specific enemy by pushing the stick towards them. Every combat is a combination of chaining attacks and counters. You can pound a specific target, or split your combos up between targets - but either way, you need to be sure you're not in the middle of a combo when an enemy starts flashing its timing warning. You need to be available to press the counter button - or use a combo that moves you out of that person's range, perhaps.
That's the heart of the combat. The offensive combos are actually the big way to control your spacing, because most enemies only attack when they're withing a specific range. By pounding on the enemies in one direction, enemies in the other direction are left out of position and unable to attack. But don't get cocky, ranged attackers exist. Similarly, you can just stand around and wait to counter the enemies, but you'll never finish anybody off that way...
There are other elements to the combat, of course. Grenades, glide-in attacks, and ranged attacks of your own, for example. But those aren't the heart of the combat, they're just spice and some glue to tie the combat to the stealth elements.
The chain brawler is kind of fun... but I think it's nascent. I think it's still in its clumsy baby phase, like Double Dragon was a clumsy beat-em-up compared to the D&D beat-em-ups. The big problem I have with the current iterations is that they feel a little herky-jerk.
In the original beat-em-ups, there was a lot of the same features - choosing whether to knock back or if you had enough time for a combo or whether you could pull off a good crowd-control move. That part is very similar. But it was tied together with a simple and effective maneuvering system where you briefly jockeyed for ideal range while shifting lanes to limit enemy attack options. You largely controlled the enemies by moving out of their range, both within a lane and between lanes.
The new system has replaced that with a countering system, where you largely control enemies by countering effectively. Sure, just like the original beat-em-ups you can control them at least partially by attacking and there are annoying enemies that can't be controlled easily using the primary method. But, at its heart, maneuver-to-control was replaced by counter-to-control. This is, at least as implemented, a weaker solution.
The biggest reason it's weaker is because it doesn't allow you to "pre-control". It's all reactive control. With maneuvering, you'd change lanes and move towards another enemy. This would give you time to attack your target enemy while the other enemy counter-maneuvers to close in on your lane and position. But with countering, you don't really have that option. You can do this somewhat against melee enemies by simply chaining your assault away from them, but ranged enemies have no concept of lane and pretty much attack as they please.
This lack of a pre-control system means you have to constantly react, wait on your enemies. It also means they have to have unrealistically rare attack patterns rather than realistic assaults.
But there are some options for adding pre-control back in.
One option is to add in stun attacks as a much more central theme. Whether we're talking about throws, leap-overs, leg-stabs, or flicking pennies at people, if you can pre-control them by stun-attacking, that's something that can free you up to launch a serious combo without interference. Don't equate this to Lollipop Chainsaw: that also had a stun vs real attack system, but for a completely different purpose.
Another option is to add in much more powerful terrain features. This can be a bit touchy with the camera, unfortunately, but by adding in simple opaque terrain you can allow the player to pre-control ranged attackers by simply taking the fight to the other side of the wall. This adds in the original maneuvering flavor, except that now instead of controlling range, you're controlling cover.
Another option is to make enemies opaque. Right now the standard approach is that ranged attackers can fire through their allies without any difficulty. If they won't take a shot unless they're sure they won't hit an ally, you can use the melee combatants to control the medium- and long-range combatants - again, through maneuvering.
Another option is to make the counters disable the enemy for a long time - five, ten seconds. This means that you wait to counter, but then have freedom to fight within that window afterwards.
In all cases, maneuvering would be done less by actually walking around and more by attacks and attack chains which move you. You wouldn't simply maneuver so that the melee enemies were between you and the ranged enemies: you'd perform a driving punch chain that cuts through five of them and leaves you on the other side.
Anyway, I like brawlers, and it's fun to think about the evolution of the genre.