Torque 3D has a browser plugin and is free. Go to garagegames and see for yourself. Also the engine is free to download from github
Thanks for recommending Torque 3D. However, I work in 2D only.
I tried to look into Torque 2D, but it is non-free ( costs me US$128 ).
They seem working well in both web client & mobile phones.
Do you guys recommend cocos2d series libraries ?