The upcoming MMO Black Gold, from Snail Games, features fighting on steam tanks and giant elephants.
There's two factions in Black Gold, split by a mountain range on the game's map, and they have very different beliefs. The "fantasy" faction has classes like mages and demonhunters and races like dwarves and the cat-like Kosh on their side while the steampunks concentrate on technology and feature races like brutes (big shapeshifters) and vampires. Humans have representatives on both sides, because you know, they like to fight each other anyway.
As for classes, there's 8 shipping with the game and they are locked to 4 per faction. The ones I was most interested in were the Inquisitor and the Mage. Each class has 3 different specializations, with the gunslinger being the most exciting for the inquisitor in that he can build and improve his own weapons. The elemental mage sounds really fun because you can use your spells to introduce devastating combinations, such as burning a foe and then engulfing him in a hot whirlwind with an air attack.
The combat in Black Gold is action-based - no auto-targeting - and you have a limited amount of abilities you can equip from your greater arsenal. You have 7 "points" of actions, and lesser attacks count as 1 point while bigger, more powerful attacks cost 7. "You could put all lesser attacks on your hotbar, that's more of a PVP build, but you're better off mixing and matching," said Colin Miller, an associate producer for Snail Games USA.