This is a mecha from an RPG I ran online. It's name the MJOLNIR: MK1 Robotic Exoskeleton.
A piloted combat robot, it stands approximately the same height as a normal two-story surburban house (i.e. about twenty feet tall) and weighs about as much as a small truck, due to advanced materials science.
The Mjolnir was designed as a commanders machine, with advanced communications equipment and sensors, and a diverse weapons suite for a variety of situations.

The game has unfortunately since fallen victim to the banes of internet RPG's - apathy, infighting, and pettiness, but at least I still have the Mjolnir!

It's a nice design, and I've always like it's shape and design.