I think there's a lesson to be learned here. Home gamers (be it on PC or consoles) expect at least 6-to-8 hours of gameplay for about twenty bucks, and you can't expect all of them to spend that time on their own volition to get better at the game, because everyone's time is precious. You want them to at the very least have a good time with what little you have and have them react with positive reviews after finishing it, which in turn spreads through word of mouth to other people who might try your game and do invest more time into it. For short amounts of content you should rely on high difficulty and replay value through scoring systems or just fun gameplay to 'pad' out the game's length while still being able to offer an arcade-like experience for the purists who in turn make superplay videos highlighting how your game is played at a very high level. Personally I would offer a STANDARD difficulty setting which includes about 80-90% of the game and lets you quicksave a limited amount of times/has a checkpoint system for people who just want to complete the game, and then an ARCADE mode for people who want to play the game the way it's meant to be played, maybe an ARCADE LIGHT and an ARCADE MAX setting to ease out the difficulty curve.
Nex Machina OTOH takes the more pure approach, with no tutorials to speak of and allowing you to creditfeed. I still don't know why you're even allowed to creditfeed in these games as otherwise players would be forced to restart and play the game like it's meant to, otherwise they're just going to complain it's too easy and too short anyways. It works very well for the niche it appealed to, but outside that niche it just didn't stick with people. Platinum games at least have the cinematic experience to create a proper experience, but Nex Machina doesn't have that either. While the visuals do look very dynamic, Housemarque's particle fetish alienated a lot of people with toasters which in turn generated less sales, which I guess is an oversight after having predominantly worked on consoles. My rig is decent and yet I still had to lower the settings to get a decent framerate. People say the visuals are cluttered, even though I think that's only the case when you're looking at gameplay footage, the visuals are surprisingly clear when you actually play the game and focus on what's important.
I think these arcade-style games should at least manage to have dynamic graphics, not necessarily technically good-looking graphics. People fondly remember Einhänder and G-Darius because they remember the cool giant robot fishes and robots and backgrounds with tons of animation and life to them with unique artstyles, kind of like with Cuphead, even if the former have jittery PS1 graphics. People will overlook outdated-looking models and textures if the game moves at a fast pace and has some life to its animations, and if it has a consistent artstyle which doesn't look cheap. Nex Machina kind of blundered here with its seemingly generic sci-fi artstyle. Perhaps they could have profited a bit more if they went with an artstyle that wasn't so expensive to develop and to get running on your PC while being more attractive.
I still think Nex Machina is the best game from Housemarque and a genuine GOTY contender which I'd rate above even Cuphead, but it is unfortunately more of an acquired taste. If you really want your arcade-style game to be successful, then I think this can be done without sacrificing the integrity of your gameplay through presentation and difficulty settings, and making your game more presentable as both a home system game and an arcade game. You might not receive the same amount of success as Cuphead without yuge amounts of marketing, but if word gets around and the game's good it should be good enough.
I believe Housemarque should downsize and focus more on accessibility without sacrifice rather than abandoning their niche, but I guess that boat sailed after the middling sales of their magnum opus. Hopefully they don't jump on the latest indie trends like roguelike multiplayer procedurally generated online card games and the like. The sole reason I bought Nex Machina on a whim is because I heard the levels were handcrafted. Too many 'arcade' games on the market I've seen are compromised with unnecessary upgrade systems and narrative cancer, especially when looking at new releases. Indie games of this level of confident minimalism, replayability, and production value are a dime a fucking dozen, and I hate to see Housemarque go out like this.