I think mugen needs to be heavily streamlined to work as an h game. Let's address the straight forward issues first. Make everyone's life simple and arrange the characters into obvious groups. There's 3 basic groups, Aggressor (Top), Victim (Bottom), and Versatile. I would focus on versatile characters first as the top row as they have the most sprites finished and options for gameplay. A lot of people want further separation of male, female, and futa characters. Personally I'd rather a small polished roster than a wide shallow one. Priority should be the quality and number of sprites available.
Next, you need a 1 hand layout. Don't try to be faithful to arcade. 6 button joystick layout and complicated combos are not an option. We're here to fap, not a competitive sweatfest. To start for player 1 wasd movement, q e lshift for punches, c v spacebar for kicks, and f for start is the best you can manage. Assuming a single person just wants to control the other character, for player 2 ijkl movement, u o ; for punches, b n h for kicks, and rshift for start.
It's too much. Take a lesson from the many lewd platformers and linemarvel inspired games to simplify controls and reduce the number of keys needed. Let's consider defensive moves. For wasd with a (block/back), w (up/jump), double tap a (dodge/backstep), and double tap d (sprint/rush). I think that's the best you can manage without adding keys or moving from the resting hand position.
Next the actual h content. Rather than a command grab combo, let's initiate with a designated button, r key. It's just out of the way, so you won't tap it by accident but still in reach. When out of range it cycles through taunts and when in range it initiates a grab h animation normally. If the opponent is stunned or knocked down longer more complicated h animations should trigger. Lengthen the stun and knocked down windows. Struggle/escape/recovery bars from mashing keys are a good way to offset the longer stuns and power of h grabs. None of the h combos should be more than 2 keys. Just r key and one modifier key to pick them and using r key alone could cycle through all of them.
The 6 punch and kick keys are the most troublesome. Usually I only want to touch q, e, lshift, spacebar and rarely use the c and v keys. q could be light punch, e light kick, lshift and spacebar could be modifier keys for medium and heavy attacks respectively. I would bind supers/finishers to c and v keys. Again only 2 key combos at most.
It looks like most of the characters came from hentaicharmugen. There are a few more recently updated characters on mugenfuta with minigame mechanics added, but the default input windows for those minigames are a little too short.
Also there's many other attempts at making a h mugen build that died out. It looks like the actual sprite artists keep choosing terrible platforms and disappearing. First tumblr, then patreon. The few remaining seem to be active on subscribestar and twitter, but a lot just moved on to other projects like 3d animation. The inherent violence in mugen in combination with h content probably sets off a lot of red flags for crowdfunding platforms. I would hope everyone interested on this forum could at least consolidate to a single thread and build.
https://f95zone.to/threads/mugen-definitive-edition-v1-0-inconsistent-champion.156579/
https://f95zone.to/threads/sf2-mugen-hunks-vs-chun-li-v8-23-jiang-tian.186982/
https://f95zone.to/threads/lapsus-m-u-g-e-n-full-kinky-build-final-lapsus.166921/
https://f95zone.to/threads/hentai-mugen-v1-1-0-mugenfighter.52911/
https://f95zone.to/threads/mugen-sailor-sex-final-fireamethyst.32175/
https://f95zone.to/threads/mugen-october-2020-2nd-tier-redflash.33483/
