I should start creating porn games. The Raana-Stuff seems to be mainly text-based/menu with static, premade porn scenes, right?
What games would you recommend for "market analysis?" What kind of games seem to be most profitable?
It depends on the scale. If you go for the big bucks, you want to sell it on Steam. Which means: no copyright infringement. Make your own stuff. Which requires artists. And if you want to sell the most copies, bought by parents and uncles as presents, it has to be child-friendly and you have to spend large amounts on advertising.
If you rather want something you can make with some friends, you still want to sell it on Steam and need artists, but in that case, you want lots of beautiful and (semi-) nude women. Sex sells. And you want to make a demo you can post on sites like f95zone, so you can make money on Patreon or equivalent payment sites.
Things like Underrail or Dominions might be the holy grail, but they take many man-years to make without payment.
For a comparison, only 4% of the games offered on steam make more money than it took to develop them. So that's your bottom line. Your game isn't going to be the next Minecraft. Keep it realistic.
And if you want to start small, you still need to post demos and advertise on gaming sites, like this one. Word of mouth and hype is what sells your game. And sex sells. But in that case, you can copy stuff.
And for the baseline: most AAA games are made for 16-year old boys, while the average gamer is closer to 40. And half of them are women, don't forget about that. They like games like The Sims and the ones which are about relations. So, no outright sex, but erotic.
