First on my list, and this is certainly going far, far back in the history of MMOs, would be Nexus: The Kingdom of the Winds. This old, two dimensional MMO was actually my entry point into the genre. So, obviously, the game holds a pretty special place in my heart.Beyond that, however, the game is amazingly still interesting after all this time. NexusTK, as it is known amongst the players, is still up and running though KRU Interactive, the former branch of Nexon Inc. that created NexusTK. The free trial for the game has been extended to allow players to enjoy the game up to level 49 without paying. This means new players can experience a good chunk of the game, or perhaps pick the game up as an interesting side game to accompany their main love.
Nexus still runs on a pretty colorful 16-bit graphics engine, which makes the game still look pretty good by two-dimensional standards. The gameplay itself is very reminiscent of Diablo, where you have to press spacebar to swing your weapon at the enemies standing right in front of your character. Killing monsters becomes an exercise in eliminating entire hordes using your special abilities and a large weapon. The game sticks to the standard four classes consisting of the warrior, the rogue, the mage, and the poet (healer), but it also allows for eventual sub-classes via quests and meeting up with members of the class you wish to be.
The game still holds its ground with the community, as other players run the two nations of the world politically and philosophically. When a war breaks out, you can be sure a player probably caused it. This makes the game extremely dynamic, as well as a roleplayer's dream. If you're a person who'd rather hack and slash than deal with roleplay, you can always journey to Mythic Nexus and engage in some pretty extreme endgame content.
If you're looking for something that may progress a bit slower and may not be entirely centered around combat, then you will probably enjoy Mabinogi, one of the newer offerings from Nexon, the people who brought you MapleStory. Mabinogi is another free MMO, so you can stop by and check it out anytime you wish. This title is one of the non-formulaic MMOs on the market, centering on the more mundane aspects of living like part-time jobs, crafting, and exploration.
While that may sound really boring, the game conduct's itself in a manner very similar to Harvest Moon, and we all know exactly how addictive Harvest Moon is. The world of Mabinogi runs on a world clock, where shops close at night and re-open in the day, certain quests only activate on certain days of the week, and part-time jobs are only available when the NPCs say they are. The game takes the social NPC system a step further by providing branching conversations with all the NPCs through keywords.
For example, if the guard of the town mentions that the resident priest lost his glasses during your conversation, you can then visit the priest and inquire about his glasses, which may send you on a quest. These keywords can also be used to find NPCs who can teach you new skills or give you information about the game's dungeons. In short, the NPCs of Mabinogi are extremely well done, and you actually end up caring for them and the tasks they send you on.
Be warned though, Mabinogi is anything but straightforward. If you're looking for a game where you can get in and skip textboxes or rush through the game to max level, you're going to want to find a different game. Dialogue is key to Mabinogi, even for those who wish to only engage in combat. Without talking to NPCs, you won't be able to find the locations of skill trainers, or find out that some NPCs literally hide skills from you until they trust you enough or you hear the right rumors. NPCs have feelings too, and that's what makes Mabinogi really stand out from the other games on the market.
Last, but certainly never least in my eyes, is Dungeons and Dragons Online: Stormreach. DDO sadly got a bad reputation upon release because people complained that they could "finish" it too easily. That it wasn't really an MMO. No, sadly, people forgot that they had purchased a Dungeons and Dragons game and came in expecting something that wasn't Dungeons and Dragons. Luckily for D&D fans, you won't be disappointed in the way this game presents itself. If you want Dungeons and Dragons, you will get Dungeons and Dragons in spades.
Most of the skills and feats from D&D 3rd Edition make an appearance in the game, all neatly listed on your character sheet and just waiting to be used. The game plays like any other MMO, but you can harness your more active skills (like diplomacy) during combat like abilities, and they also come into play as you interact with NPCs. During combat, you even get to watch as the infamous d20 is rolled off to the side of the screen during each one of your attacks, so you can see just how badly you botched your last sword swing.
Where I think the game really stands out from the other MMOs is in two areas. One is the Dungeon Master, who cleverly narrates each of your adventures, giving you the true D&D gameplay in an online space. The second, and more important aspect of the game, is the use of passive skill checks. The computer, playing in the role of the Dungeon Master, will make skill checks for your character without you even realizing it. If you pass, you'll receive a message that other players may not receive, like how your character notices the secret door in the wall or the trap the Paladin is about to step on. This feature is something no other MMO embraces so well, and it leads to some really memorable adventures with your party. In short, these two features alone make it a must play.