Pokemon Planet vs Tartaros Rebirth
Pokemon Planet
Pokemon Planet is a Pokemon-themed, MMO adventure-RPG where you'll not only get to strive to "become the very best like no one ever was"; you'll also be able to assemble a team of Pokemon from various generations/regions (except the ones from Alola). It even features graphics that will definitely twinge that sense of nostalgia in your heart, especially for those who have loved Pokemon ever since their childhood days.The game plays out pretty much like the usual handheld Pokemon games of old, except that this time around, the game is an MMO and hence, you can actually interact with other players in the game. This does make trading Pokemon or dueling a lot easier. However, since the game is not Nintendo-affiliated, the developers are restricted from using certain assets of the franchise, which apparently includes animation and sound effects, but oddly enough, that exclude all the Pokemon designs and every other game element in the game like Gyms and Pokemon Centers.
Although Pokemon Planet is not a Nintendo-created game, it is the sort of Pokemon game that fans of the franchise have always dreamed of. It has the entire package, from the nostalgic graphics to all the Pokemon you can possibly catch (and then to duel other players with). Personally, I believe Pokemon has always been a game that's just primed for an MMO game, and Pokemon Planet simply one-up Nintendo by turning that into a reality (first).
Tartaros Rebirth
Tartaros Rebirth is the revived version of the anime-themed MMORPG that was popular back in the 2000s, Tartaros Online. Featuring everything you know and love from back in the day, this game has something new to offer as well, such as brand-new storylines. Like the original, you'll get to play as one of nine unique characters, each with their own personalities and skillsets. You can switch between them while you're in town, but not in dungeons or instances. Questing is the main way to level up in this game and the grind is real. However, there are tons of places for you to explore and you can even use higher level characters to complete quests for your lower level characters to turn in.The combat system is rather clunky though, so is its controls with keys that you'll probably have to rebind. Battles are played out in a semi-action-based manner, but since you can't really dodge, block or dash away from danger, all the "non-action" can be a bit underwhelming. Not to mention, the graphics isn't updated somehow and although it may have been acceptable back then, it is definitely not something that will appeal to players in this day and age.
So, in short, Tartaros Rebirth is a great anime-themed game to play, despite sharing many similarities with Dragon Nest, for nostalgic purposes but if you're simply looking for a new anime game to play, you might have a better time playing Lineage II: Revolution.