TetraVaal

You could use it to fight a boss in terms of scale. Look at the size of the Covenant's heavy assault platform (Scarab). That thing is about 20 meters tall and 50 meters in length. For Chief to pilot a mech that's around 10 meters tall or so with thrusters for elusive movement isn't exactly too out of the ordinary.

I like the idea of having mech in the Halo universe. It doesn't even have to be reoccurring so for those that aren't fond of the idea they won't have to use em' much. The thing is, if 343 is to introduce a mech in 'Halo 4'-- and I hope that they do-- I want it to be something interesting in design and preferably bi-pedal. However, I'm sick of the ugly militarized style mechs we see in Western entertainment. Ideally, I'd go with something about 7 to 8 meters tall with a traditional cockpit for Master Chief and aesthetically similar in design to the Mk. I prototype armor. That's just my thoughts, though. But just the idea of Chief piloting a mech makes me very happy.