WoW is cool, but I kinda like Dot.A more.
I'm currently playing Armored Core SL.
Hardest game I've ever played imho. The category is Scifi-Mecha.
You started with a robot with VERY low abilities, etc.
You need to finish missions, but every damages done on your robot counts, and you need to pay for the repairs.
Now I ended up in "minus".