I think the problem with a game like this really isn't the quality of renders or even the story, it is more to do with the fact that the vast majority of devs working for big cash gains need to spend a lot of time going through all the very successful games to figure out what made them successful in the first place. Thrre is a bit fo a checklist but it doesnt seem to be all that large really
If I was going to make a game the number one thing is to avoid absolutely anything with NTR, that clearly is a huge turn off for the average punter, the next would be to really sit down and analyse what tags generate the most interest from folks willing to shell out money. Basing most of what I know on the success of GGGB it seems giving people choices that really matter, multipath sequences and customisation of characters appearance really seems to be the way forward. Incest content while wildly popular among the folks here is a monetary block given patreon rules and other pay methods so not including that or as GGGB did, burying it so deep the average punter would never find it is a good option.
That part of the analysis would take several months to do to really get a good idea on what kind of content "sells". The next part is to figure out your marketing strategy and how you organise your payment tiers and rewards system on patreon. This really seems to be something that most devs do a poor job of and yet it is critical to your income stream. After sorting that out is figuring out how you promote your product, where and how much you spend etc youtube, facebook all the social media platforms and forums out there.
Successful games are not only about a good story and kick ass renders, in fact looking at GGGB again, I played it despite the art work and having awesome iray renders does not in itself guarantee success, as we look at the possibility of PU stopping as an example of this. One other thing that makes a game more successful than others is getting patreons involved in the actual creation process, offering up choices of characters from which they can select, allowing user generated ideas and adding them as side stories to the main story line etc
Then finally, writing the story. A lot of fellas seem to sit down and start pecking out the python code, but a really fleshed out story board with the different paths laid out before you even open up ren'py is the way I would go. Plus of course you need the right mix of story and adult content with a firm schedule of release. Again looking at GGGB as an example. Preview, alpha, beta final gives your customers lots of interest and maintains interest. Modular sub story lines that can be dropped and others picked up as you review client interest is also a good idea while driving forward with the main thrust of the story will help maintain long term interest
And maybe finally, the most successful games are done by teams from what I can see. A writer writes, a coder codes, a render man renders. Thats my two cents worth based on the dev here closing up shop early. At least he took the time to finish it in some way rather than walking away.