I agree. I loved this game, but I only played solo. Even with multi-player options (I didn't have the "Fire and Sword" version) I'm not sure it really constitutes an MMO.
For anyone who hasn't played Mount'n'Blade, it's half strategic combat sim, half 1st person RPG. The world is dynamic and changes every game. As do quests, faction ethics and such. Only the landscape and a few names and basic quest outlines are static.
The play engine is very much like Oblivion or Two Worlds. Players can hire mercenaries and pledge allegiance to various nobles veining for power, which is when "quests" come into it.
There are numerous 3rd party maps and mods for the game to take you from the normal Medieval setting to anything from the American Civil War to the Star Wars universe.
You get to "ride a mount" (obviously) and use melée and ranged weapons from bows to crossbows, either from your mount or on foot, which allows mods to implement guns and blasters and speeder bikes etc.
TaleWorlds