TERA (The Exiled Realm of Arborea, to be precise) is a game that might revolutionize the way people play MMOs, if not for all the ways in which it doesn't.
Combat in MMOs these days is most often played using the model popularized by, though certainly not invented by, World of Warcraft. The character selects a target and begins to attack that target with his or her weapon of choice; the target responds in turn. The player presses buttons on the keyboard to activate the character's special abilities, and both parties slug it out, trading attacks until one of them retreats or falls.
TERA (mostly) throws that kind of gameplay out the window. You still have hotkeys to press in order to activate your abilities, but there aren't any autoattacks. Rather than the success of your character's attacks coming down to an arcane mathematical equation judging stats like "attack hit" or "dodge," the success of your attacks depends on your aim. Your character's attacks and abilities are all aimed at the targeting reticule in the center of your screen, meaning that success is up to the player rather than stats.
It sounds like an obvious design choice, because it's the way that regular action games have worked for years, but it can't be overstated how well this mechanic works in an MMO. Battles in TERA against the game's BAMs (that's Big-Ass Monster, and yes that's the official term for them) are fast-paced and mobile encounters that rely more on player skill than the character's numbers. The Berserker class can deal massive damage, but attacks are slow and missing one charged swing could set you back precious seconds. The Lancer tanks manually block enemies' attacks with their shields and Warriors nimbly leap out of the way to avoid damage entirely. Even healers, whose play in MMOs has always been derisively compared to a mindless Whack-A-Mole, must manually target their life-saving abilities by locking onto teammates or consecrating specific patches of ground.
The action-based combat means that TERA is genuinely fun and exciting to play when compared to so many of its peers, and if this innovation were copied by every other MMO to come, it'd be a godsend for the genre. It's a good thing that TERA's core gameplay is such a triumphant success, because the rest of it feels somewhat dated and uninspired.
TERA manages to weave sort of storyline about sleeping titans that dreamed up the world and extra-planar metallic invaders that seek to wake them and destroy all of reality.It also kindly makes it simple to follow which quests are part of the main story progression and which quests are just there for a chunk of XP or cash - but it all feels secondary at best. MMO stories are typically regarded as uninspired fantasy tripe, and while TERA seems to be trying its best to weave a rich, fascinating mythological arc, it does a poor job at selling it. In particular, the cutscenes with your character are overwrought and come off as a little silly - having a snarling, gruff-voiced general point his sword at your character's throat isn't quite as intimidating when your character is a fuzzy badger-man and the sword is actually pointing well over his head.