I'd rather post in the other thread that was linked, but I got some red text yelling at me, so I'll post it here.
I'd like to think that beat 'em ups are my forte. I flippin' love them.
I'm going to talk about a few that are incredible. Post a link to a terrific article written by the programmer of several of those games. Then share a bit on my own philosophies about the genre and lessons learned while making Aces Wild.
I break it all down at the bottom if you wanna skip the game by game breakdown.http://www.tylerdoak.com/?p=122
<--There's the article. It's really good!
Technos: Double Dragon 2/Double Dragon GBA/River City Ransom/Kunio-Kun
Capcom: Devil May Cry
Ninja: Ninja Gaiden
Technos sorta started it all off with Renegade, but made it a hit with Double Dragon. They also made River City Ransom, which, we all know, is great too.
Double Dragon was basic, but had many elements come together to make it great. You had a nice concise moveset. Enemies could approach you from 360 degrees. Many enemy types. Several weapons. Hazardous environments--which had lots of aesthetic variety as well.
The moveset also increased as you played (RPG LM-entz!). But more importantly its variety meant you had choices to make based on what was going on. The basics of it is slow and strong vs fast and weak. This is simple enough, but many beat 'em ups ignore it. The next part goes along with game design in general: The more actions you have and the more objects you have to act on them, the more variety you have. Because you have several moves, times several enemy types, times the current environment and the actions you take alter all of those at once, you have lots of variety. Most beat em ups boil it down to just actions vs enemies and that's a whole dimension of variety your missing out on.
River City Ransom did the same thing, only it was a console game so the story and rpg elements were ramped up. Also the action was faster, more cartoony and manic. Both games also had weapons which provide a "sanctuary" of sorts that I'll talk about more later. Both of those games had 2p coop. Instant win if it wasn't already. I mention specifically DD2 and DDGBA because they are my favorite. They are incredibly solid and epitomize everything that made Technos great.
After that, we had Streets of Rage, all of Capcom's cool beat 'em ups, and wacky obscure ones like Knuckle Bash. These games were very solid but mainly carried the beat 'em up torch in a pretty consistent direction.
Then we had Devil May Cry and the new Ninja Gaiden. These were gritty, intense, crazy, hard and 3d. The 3d isn't that big of a deal as double dragon basically played the same way spatially, though the immersion was greater.
Instead of having that extra environment element strong, these two games focuses heavily on player ability. You were super human and super badass. Each one took a different philosophy. Devil May Cry gave you tons and tons of moves and lots of enemies and epic bosses. It was your job to use those abilities to create variety. Ninja Gaiden's approach was on the other end. That game wants to kill you. Every enemy is a huge threat and you have to block a lot and really think hard about what you want to do. Which leads to another "innovation" these games had. Defense, you could block, dodge, run and jump dynamically to avoid enemies. This is more important than you might think. In previous games you simply walked around to avoid enemies and some others allowed you to block.
To paraphrase from the article I mentioned, blocking is bad. It is boring and makes you wait for the enemy to act. Dodging is a reaction. When the enemy attacks, you react and dodge accordingly. If you think a bit, you can see how this already adds a new dimension to the combat. You actually have defense and offense to worry about!
So out of the blue we have this crazy game called Godhand. You had TONS of attacks and tons of defensive actions. In Godhand, they did something great. They gave enemies defense. You had to not only worry about attacks in the traditional way, but the enemy might block which means you have to act differently. In Ninja Gaiden, the correct action isn't always clear and enemy blocking is frustrating. In Godhand, to quote designer again, "it's an opportunity." By breaking an enemy's guard, you can stun them, then really go crazy! So now you have 3 basic actions--attack,dodge,break-- that work better or worse depending how the enemy is acting. Then within those design spaces you have different types that have all sorts of different properties. Should I sidestep or duck? Should I punch or kick? What's great about these design spaces is that the game presents you with the variety: enemy block, enemy attack, enemy open: but you get to decide the specifics. So it's a terrific dance with the game and its enemies, while you get to be a bit creative when the tempo changes. Godhand's attack system was a bit lacking despite the number of moves. Basically you just wanted to abuse the best move over and over again and sometimes use one that had different properties. Bayonetta solved this problem and combined two aspects. You have 3 basic buttons in Bayonetta: Quick attack, Strong attack and dodge. To get to more skills you have to work your way through a combo. So you mash on Quick attack, then hit Strong attack to get a REALLY fantastic attack. It takes time, however, to reach that move, so you may opt to go for a lesser attack, but the payoff isn't as great. Further, while you're trying to reach that attack, AN ENEMY ATTACKS! So you have to dodge and risk losing your combo spot(though you can retain it). BUT! If you dodge right at the last second, you get WITCH TIME! This is like the guard break opportunity in Godhand. It gives you free reign to really wail on enemies. Which brings us back to that sanctuary thing. All of those games have limited powerups that allow you to be really powerful for a short time. Godhand and Bayonetta have both special attacks, context sensitive attacks and weapons that do this. Double Dragon had weapons. DMC and NG had special moves and forms.
One of my basic design philosophies is, again, actions vs objects. Just a quick aside, Yoshi's Island really epitomizes this. You can lick, stomp, jump and shoot. All of those things affect both the environment AND enemies IN DIFFERENT WAYS! Really keep that in mind when designing action games and beat 'em ups.