Game developing on Ubuntu

Just for fun, I decided to start browsing the web for game libraries and or engines available on Ubuntu. Found a bunch.

• Panda3d
• Crystal Space 3d
• OGRE
• Irrlicht
• Blender
• Delta3d
• Raydium

So I have a couple questions:

• Has anyone who is reading my blogs, programmed or used any game engines on Ubuntu? Which ones? How was your experience?

I am considering making a MMORPG and would love it if I could make it work for both Ubuntu and Windows. Give me some feedback.