Nowadays it's easier than ever for aspiring game devs to create their own pieces of art. Slay Together is an example of just such a hard working developer, as its developer tackles the massive project on their own.
Per the game's Steam page, Slay Together aims to be a game in the vein of Metin 2, Flyff and Dragonica. It's all about kiiling monsters and gathering loot. Since it's being developed by a single person - 5 months so far per a Reddit post by the developer - it's still in its earliest stages. However, right now players can jump in and level to 25, collect gear and complete a rather linear questline.
In the future Slay Together hopes to get its first dungeon, weapon based skills and a more advanced character creator in the game according to its Steam page. However, players who want to hop in and provide feedback can do so now as it's free-to-play right now. It'll be intriguing to track Slay Together's development as it continues, but building an MMO from scratch with a large team is daunting enough - by yourself is incredibly ambitious.