That is why l am after anal only, it implies freedom in it. And the above Kiss game, does that well.
Which cannot be said about some of the other games listed here.
I really don't know why, for example, you gave 'the Fixer' four ticks, when it's obviously not an anal-only dedicated game, but a poorly executed knockoff of 'Degrees of Lewdity', just with better graphics and much worse sex scenes. The game's main sex obsession seems to be not anal, but impregnation and deflowering, but even those fetishes are seriously underdeveloped, not to mention the entire game, still struggling with the basic mechanics and engaging plot.
Then, there's 'My Pig Princess', a furry game with cute graphics, which so far has only one 'anal-only' scene out of disappointingly too few sex scenes overall. The main theme of this game seems to be drawing anthropomorphic mammals with tits. The main fanbase are those who think they're furries, not genuine ass bandits.
'Project SAGE'... I don't know if we're talking about the earlier, raunchier version, where the MC actually gets to fuck guys and sure enough, to protect her virginity she does anal, or the toned-down, later version, where all she does is anal masturbation, occasional 'blackmail' blowjob and teasing the player with sexy outfits for hours and hours to no end? At times, the game feels like a boring session of D&D, where all the players and the GM too are wearing buttplugs for some reason.
When it comes to freedom of choice, only Karryn's Prison, Degrees of Lewdity and most of those KISS simulators provide that and take extensive anal play or even exclusive anal play into account. So to add to that, if they haven't been mentioned yet, I propose:
'Freecities', especially the Pregmod, adding extra options, some those quite extreme. While the game is not finished and thus seriously unbalanced and it's basically a text based repository of all fetishes known to men, not just anal, it lets the players induldge their ass-fixations quite deep, allowing to build an army of buttsluts who love anal, just anal and nothing but anal. And it has ass pregnancies too, so you can modify your poor ass slaves' genitalia into cloacas of sorts, which is quite out there, if you ask me.
'Hypno App', yet another molestation simulator, quite similar to those train perv games. Here, instead of mass transit shenanigans, the player is using a hypnotizing app on his phone to render his uptight female classmate immobile, so he can do stuff to her. There's only a bunch of scenes, unfortunately, and while anal is not the main focus of the game, your playstyle can make it so.
Tales of Divinity: Rodinka's Lewd Adventures: quite funny, though boring at times, Slavic-flavored RPGM seems to focus on anal only quite strongly. It's still work in progress, but until the last release there was not even an option for the heroine to offer her pussy. Yes, offer. While the MC is a properly naive, young girl, there are no non-consensual scenes there.
I also would like to mention
'The Poor Whore' which, while featuring a non-virgin MC, allows the player to do an anal-only run, including expansion and fisting. It's quite an old RPGM, sadly with no GCs, but a lot of really debauched textual descriptions. It's also heavy on BDSM, if anyone's interested.
'Prepare Uranus, Exploring Black Holes for Adults' - already mentioned above - is a properly anal-only dedicated game, where vaginal sex is not even on the agenda: the rear hole is the right hole, just like the Universe's Maker intended. The design of the game and the plotline are weak though, but for those who'll suffer through the grind and the game's lame sense of humor will be rewarded with scenes of TAP involving oversized dicks from outer space and hectolitres of alien cum with superlubricating properties.
