Although I have to sa I'm a hardcore fan of the genre, so I'm pretty much making it on terms that (japanese) fans of the genre demand.
And most important rule on what makes a good beat'em up, imo.
Crowd Control!Beat'em up games are about managing crowds. So crowd combat is essential focus on making a beat'em up game. U need to tune ur fighting system on fighting multiple opponents. Gamers have the wrong examples. SNES/SFC beat'em ups should NOT be taken as example for ur beat'em ups. And that's because SNES/SFC processor cannot generate more then 2 enemy grunts on the screen for beat'em ups with final fight sized sprites. Which means the 2 grunts perform either too much damage or are HP sponges. Both are not good for the pacing. While their are some close examples on consoles, a beat'em up/belt scroll game should play as their arcade counterparts. Generate at least 8-12 enemies on screen, but balance the HP so that it doesn't become tiresome and stale, so the point of combat is control the crowd effectively.
This my friends, makes beat'em up/belt scroll games not stale unlike the bad mouthing by videogame press that beat'em ups are repetitive.
I have some beef with IGs beat'em ups, they are quite crunk games! But the focus on juggles can be boring. I don't if it's me but juggle combo-ing bosses once in a while is fine, but to constantly perform juggles is jut plain repeptitive. Crowd control is exhilerating, and keeps u on the tip of ur chair.
Most of the console beat-em-ups of the 90s were actually impossible to win, because no matter how good you were you always traded blows with enemies until you lost by sheer attrition.
Maybe u don't understand the fighting system...?
I am making a belt scroll/beat'em up game myself, called Dragon Arm.
It's inspiration for it's setting is the new school HK movies. But there's a good bit of influence from old school 60s/70s/early 80s Shaw Brothers and Taiwanese swordsplay in it as well (the bosses, mainly), think Master of the Flying Guillotine or 5 Deadly Venoms.