I'm a writer and indie game dev of indie games with cum in them. One half of @BPGames. Most recent project - Opportunity: A Sugar Baby Story.
Other Accounts
@zippity - goofy porn game screenshots
@BiggHoggDogg - this is where I do most of my porn following & sharing
@BiggBlast - high-volume shitpost/screencap posting
Current avatar by @julian!
After three years of covering adult games for my newsletter, and seven years attempting to will my own into existence, I can only conclude that shit's just really, really hard. But adding and tweaking gameplay mechanics is easier than writing a compelling narrative that weaves sex into it in a compelling way. Very few have pulled it off!
I'd say that tweaking mechanics might be easier if the usual engines of choice (RPGMaker & Ren'Py) weren't so rigidly created for a very specific purpose, and at some point these custom mechanics are so unrecognizable from the base engine that they might as well have made these games in more generalized engines that would probably have allowed them more freedom. I'm more than confident you've seen the numerous 3D Ren'Py VNs with looping movie animations, some of which sport handmade Blender models which are rather high quality... but there's so many movie files that it artificially bloats up the filesize of the game. It's not efficient or optimized in the slightest. I'm just so confused????

I think the best answer to this problem is that most people who are making erotic games that go much beyond basic Visual novels are Horny programmers first and writers second.
That's probably a fair assessment, though with the number of erotic Twine game developers (or even just grab a fanfic writer, there's tons of them) out there, one might hope that a competent writer and programmer might see a mutual benefit in working together.