Animal sims games.
wolvden — you're aware of lioden, so you may be interested in its sister site. wolvden's gameplay is very similar in many aspects and different—maybe even evolved, I'd say—in others. its community is significantly smaller than lioden's, but still immense compared to the other sites on this list pure felinity — possibly the only realistic cat breeding sim still in existence. it's archaic by modern standards, it's incredibly niche, and most would find the visuals and gameplay frustratingly barebones, but its art and breeding mechanics are completely unique. I think it's pretty special, and its small community is tight-knit and dedicated. however, I would strongly recommend using the old layout, especially on mobile felisfire — basically a more-or-less evolved version of mweor with some excellent art (and recently some that's less-excellent). unfortunately, I feel its gameplay has depreciated steadily since the site was bought by new management about five years back, and it's lost many players. its breeding mechanics are also questionable, imo. however, it has a variety of unique features and I would still recommend checking it out if you find its premise interesting khimeros — similar to mweor, felisfire, and lioden. it's kind of a quirky site, which is saying something for this list. you can own and breed a variety of fantasy species and mini-pets and explore its world to scavenge items. I've never been an active player so all I know about its breeding mechanics is that they exist and are likely similar to those of mweor and felisfire I can't vouch for the following sites as I'm not an active player, but they should fit your criteria: alacrity sim (realistic dog breeding) cyska siberians (siberian cat breeding) dogdayzz (dog breeding) gryffs ("gryphon" breeding) howrse (horse breeding; surprisingly mainstream in its day but widely considered pay-to-play by the virtual pet community at large) lucky lapine (rabbit breeding) flight rising (dragon breeding)