The mecha in my story are referred to as hanzers.
If you played alot of videogames like me, you'd know that the word hanzer is an homage to the word Wanzer, which is what the mecha were called in the Front Mission games.
Of course, if you played the games, you'd know that they come in all shapes and sizes, and so do the hanzers. I think, the main difference between them though, is that wanzers embrace their robot nature, and move in a very stiff, mechanical manner, while hanzers employ fictional 'nano-muscle' which allows them very fast and flexible movement.
All cockpits in hanzers are in the middle of the chest, but some are chest loading (as in, the pilot gets in through the chest) while others are back loading.
Normal Hanzers are large, about wide enough to fit into a city street, but smaller ones are made, as well as larger.
"Nano-muscle" isn't actually muscle in the sense of being cells, but instead it's thin strips of plastic that has billions of nano-machines woven into it that contract when an electrical current is passed through it, thus allowing it to act like muscle. It doesn't self-repair like real muscles, so they have to be replaced every now and then. The output power of the muscles is dependant on their quality and make, and thus the newer hanzers are oftentimes stronger than older ones. This has the side effect that electrocuting an hanzer will cause it to spasm, and that injuring one will cause it to 'bleed' the conductive fluid that allows the muscles to work. The bleeding would only be limb dependant though, so having an arm ripped off wouldn't cripple the other limbs, or having a forearm crippled wouldn't disable the hand attached to it.
Hanzers can be equipped with many kinds of hanzer-only armaments. There are giant rifles, pistols, shotguns, flamethrowers, tazers, grenade launchers, and other things meant to be held and used by hanzers. Hanzers can also be specially customized to have weapons built into the frame. For example, spikes or knives can be placed on the fists, an abdomen can have many rocket pods built into it, or an arm can be replaced with a giant machine gun. There are also melee weapons for hanzers, including knives, bayonets (attached to guns), swords, axes, and hammers.
The inside of the cockpit is different for each hanzer, however, each follows the same basic layout. That being that there are two handle controls that control the arms, and two foot controls for controlling the legs and feet. Besides those, there's a panel of other controls that allow control over the more subtle features of the hanzers, such as as auto-pilot, video communication with other hanzers, or air conditioning. To allow easy seeing, there are several large monitors inside every hanzer which allow the pilot to see in the front, sides, and behind the hanzer. There are a number strategically placed cameras on the outside of every hanzer that allow these to work, and if these are disabled because of any reason, then the pilot is essentially blind. Any of the controls, or the position of the cameras, can be customized to better fit the personal style of the pilot. Most hanzer pilots will use the pilot's seat, which are the chairs they sit in whilst piloting, but some are uncomfortable with these have them modified as well, removing the arm rests, forcing them to recline, or removing them outright and use all the controls whilst standing.
The cockpit itself is held in place by a series of shock absorbers so that sudden movement and the harsh vibrations from being attacked don't rattle the pilot too badly. There are also shock absorbers in the knees, arms, and other parts so that the hanzer can run, jump, block, and other things without damaging itself.
The feet of hanzers that are designed to travel primarily over smooth surfaces can have large feet and wheels, and while coast along smooth surfaces instead of walking. Those meant to travel over rough surfaces will have very high traction feet and will need to walk everywhere.
Hanzers can also be outfitted with boosters, or jets which would allow it to lengthen jumps, increase running speed, slow the descent of falls, hover for short periods, or, if used inventively, attack.
All hanzers are outfitted with armor to avoid having the nanomuscle damaged. The actual specifications of the armor very from hanzer to hanzer, and can be light, heavy, or specialized to better fit that specific pilot.
For security reasons, most hanzers are intended to only be piloted by one person, and to facilitate that this is the case, all hanzers have fingerprint scanners and locks so that only the intended person can activate that hanzer. This makes it exceedingly difficult to hijack a hanzer. This also allows for the owner to personalize their hanzer as the equipment is unlikely to be used by any other person.
Hanzers can be painted or colored, and will often have a specific insignia to signify which country the pilot is fighting for.
I asked Fault to draw some pictures, and he was nice enough to provide some very good art.