Put Monster Hunter's monsters into Ark with this mod

You don't get to ride the Rathalos. You are the Rathalos.

First Pokémon, now Monster Hunter. Modders continue their noble work to combine every game with every other game, as showcased by the efforts of garuga123, whose Monster Ark: Hunting Evolved allows you to play Ark alongside some of Monster Hunter's most iconic beasts including the Rathalos, Deviljho, Barioth, and more.

It's surprisingly fleshed out. Originally I figured garuga123 had simply reskinned some of Ark's dinos to look like dragons, but they've actually imported the animations as well. Any Monster Hunter fan will tell you that these creatures' personalities are defined more by how they move than how they look, so being able to run around with a Rathalos and have it act like it does in a proper Monster Hunter game is fantastic. An interesting twist is that you can't actually ride any of these creatures but control them directly. The original intent of the mod was to roleplay as them—which I never realized was a thing that people wanted to do.

Along with the animations, each monster also has access to a few of their signature abilities. As a Rathalos, you can shoot fireballs from the sky. Uragaans can form up into a ball and roll around the island, and the Lagiacrus can charge up a blast of lightning and devastate anything nearby. If you bump into a wild Qurupeco, it'll even mimic the call of other animals so that they come to its aid—just like the bastard does in Monster Hunter. 

Aside from some problems with clipping into the environment the only drawback is that the mod will take some effort to get working fully. Right now the only way to encounter these beasts is to spawn them in using the console commands listed in the Steam Workshop description. That's a bit disappointing if your goal is to, well, hunt for one in the wild. Fortunately, players have conjured up some code you can easily paste into a game file which should cause the creatures to begin spawning naturally in any of Ark's maps. Instructions on how to do that can be found here.

If you want to play multiplayer but don't have the patience to set up a server, this one uses it. There's even more listed in the discussion forums if that one doesn't work. Consider joining the Discord chat server so that you can give any feedback or find others to roleplay that love story between a lonely Rathalos and Rathian you've had in your head for so long.