well it didn't seem to have the limit in the game (played L2 for many years), I remember storming some castle raids with more than 200 people on the attacking side...
but anyway, Unreal 2.5 is definitly not what we are going to use

Can we have another hint? I love love a good mini arg.(The big ones piss me off.)

Frostbite 3 engine for destrucibility and epic scale.

This incorrect. The UDK limits you to 64 player games. However, the UDK is an advanced editor for the Unreal 3/4 Engine, not the engine itself. To license the full Unreal 3/4 Engine is extremely expensive.

There is an MMO ready toolset called Atlas for Unreal based MMOS (source).

That said, Unity makes more sense. Less expensive and has several substantial updates in the pipe, including a very robust GUI system.

some month ago miguel on a twitt say te engine are two one server side and one client side

aha! Thats one we can mark of the list!
http://en.wikipedia.org/wiki/List_of_game_engines

...The list of +63 game engines :s

Good, Unreal 2.5 simply isn't a powerful enough engine.

http://www.moddb.com/engines 502

I'd say the 63 would be a bit more accurate, I went down on that list and there seems to be a lot listed for 2D games specific granted I didn't go the whole 502 list...but I hope they arent using a 2D engine for Eternal Crusade

Isometric 2D third person MMO shooter-RPG. Mmmmm precious.