Let me put this short sweet and to the point.

I want an Engine that:
1. Allows me to create Multiplayer Online Games that can be played in a browser like Runescape (Massive comes later as all experienced Game Devs know, and I'm not making the gameplay like runescape...my gameplay will actually be good o.o)
2. Uses 2D Sprites or 3D rendering, not text based graphics or 3D meshes (I'm not trying to kill someone's browser here o.o)
3. Implements it's own scripting language or allows me to edit parts of the source code so that I can implement a guild system, spells, and other features as I please (I can learn just about any computer based language within two months if I try)
4. Activates like Realmcrafter, simply put I don't want something where I'm REQUIRED to go download a Java SDK and compile everything just to start making the game, though I guess I can live with that if I have to.

Thanks.