niche genre wth hardcore scene and pregnancy , interspecies scene are bonus
If you care mostly about the scenes and not the game part to consider similar, there are some.
First there's the first game, Cursed Armor. It has not only similar scenes to this one, but has a horse marriage plot line that is just great.
Now, for my suggestions. I would like to point out that I didn't filter these by being similar in terms of game play to CAII, this list is going off of just the themes you requested.
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If you want bestiality then you really can't go wrong with:
Slice of Venture Origins - Amazing art and great scenes. The corruption plotline works wonders and there's even some more niches to explore. Only big issue is that it isn't really a game. In terms of interactivity it sits somewhere between a VN and a dating simulator. You interact with it enough that it isn't a VN, but you're also mostly walking around to find where the scenes and story are. The story is pretty decent though.
Syahata's Bad Day -
Amazing art. Amazing game play. Only real problem with it is that it ends. Here's my full
review if you want to know more. There's also basically no story, if that's a deal breaker to you.
ThornSin - Currently in development, but what is already there is just amazing. More interactive and better produced than CAII, but also shorter and with very little story. It not only features bestiality, but also pregnancy and monster birth. And it's also interactive and sprite animation based, no static CGs here.
Cocoa and Taro - Not in the same level as the others I suggested, but it's my hidden gem. The story is fun, it's short and the scenes are decent. I like and those who play it seem to like it too, but it's not well known or anything.
Tentacular - Basically beastiality all the way down. I don't remember a single scene involving a human in this one. I don't personally like as much as others here, but a lot of people seem to love this one. The reason for my distaste is that I don't think it has enough of a story for a VN. The scenes are great, but the way I see it, if you're making a visual novel, it needs the visual
and the novel.
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If you want pregnancy, then I suggest:
Lust Epidemic - as a game it's not great, but the 3dcg is decent and the story is really good. It's also the first game in a trilogy that get
A LOT better in the latter installments (though only the first one has any real preg). I say it's not a great game because, similar to SVO, it's a walking simulator. Only this one has a bunch of item based puzzles to block where you can go and has a bunch more spaces you have to check in order to find the thing you need to progress.
It's mainly annoying because you are working on several different threads at the same time and you'll inevitably forget about what you needed to do in each. It's saving grace is that it has an item that basically tells you where you need to go to progress. You'll be using that feature a lot.
There isn't a lot of pregnant content in this one, but it's one of the two games I can think of where you actually get to screw the pregnant girl instead of being the pregnant girl.
Four Elements Trainer - The second game I can think of where you screw pregnant ladies. This one has more preg content, but it's still not the main focus. Plus it's mostly centered around the latter part of the game. It's a VN so basically no interactivity and a lot of reading. Don't be deceived by the beastiality tag, it's just a couple scenes among a hundred. Also don't reject the game based on the first book. It took them years to craft this one so the art and variation gets much, much, better as you progress over the books.
The Agnietta (and it's sequel) - Amazing art and great gameplay. I prefer the first one, but they're both good. One caveat is that pregnancy in this one is a sprite based in game event, meaning you don't get to see CGs around it. There are a couple CGs where you get impregnated and then see the aftermath of the birth, but nothing incredibly complex. Another caveat that I personaly consider a good niche but might not be your thing is that this one is mostly tentacles/huggers/"werewolf" and similar, you shoudln't expect to see human on human action.
Melty's Quest - Amazing anime art, decent (basic RPGM) gameplay, really good story. It also has plenty of clothing options that cater to a lot of diferent tastes. Preg content is fairly limited though. You get fucked when losing and there's a chance you get pregnant. Pregnancy is basically a punishment that forces you go to back to the city to deliver the monster baby. There is a birth scene though, a fairly good one at that.
Hazumi and the Pregnation - Decent story, okayish gameplay. Mostly there for you if you really want pregnancy. It's the sole purpose of this game. At that it excels, but the art isn't for everyone and it's not as much of a game as the others here.
Kunosuba Curse of the Defeated Sow Knight - Same as the previous one, but with more interesting scenes imho. The art might a bit worse though.
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Here some more games involving weirdness. They might have preg/best, both or neither. It's mostly suggestions based on what CA offers that I think a connection in taste can be made.
Captivity - COD: zombies with monsters/insects/fnaf-robots. Pregnancy and birth in a couple of the stages. The gameplay is amazing and it's also decntly hard and fun. It's mainly niche because of the insects and stuff. It's also all in game sprite animations, so nothing too detailed. Basically no story.
Mystic Knight Maya - Solid gameplay. Plenty of sprite scenes. Lots of best, some preg, decent ammount of transformation. Caveat is all the vore, lots and lots of vore. It's all sprite based so nothing too graphic, but it is there.
Odyssey of Gianna -
THE transformation game. I honestly can't believe this one isn't 10 times more successful. Has a decent story, amazing gameplay (for RPGM at least) and a huge selection of weirdness. There is one pregnancy stat, but it's not a big part of the game. This one is mainly the transformations and mind control. Main issue with it is that the game is so incredibly complex that the engine gets in the way.
Lastly, I would like to point out that both preg and best are categories in the forum, meaning you can search for games containing them
here. Just filter by tags on the side and try ordering by score or thumbsup.