Like most guys, I've always had a soft spot for giant machines. It began with construction machinery when I was a kid—big cranes, dump trucks and the like. It continued with glimpses of giant robots on after-school television and saturday mornings. Even so, I was (in the wilds of South Dakota) never really exposed all that much to Japanese Anime like Robotech or even Voltron. And then came the AT-AT walkers in Empire strikes back. They made a big impression on me (no pun intended) and they were probably the reason I eventually got into playing Battletech (a tabletop wargame with giant mechs piloted by people). Strangely enough, I never liked giant Robots (such as the transformers) as much as I did the piloted vehicles. I like the idea of the human element. Its just more interesting to me.
All this being said, walkers never really played a huge part in my Star Wars campaign, even though I did enjoy using them. I never really branched out from the two basic types of walkers: AT-ATs and AT-STs. It wasn't until much later that my thoughts turned to including something new. It began with the Expanded Universe inclusion of new walker types: the AT-PT (a tiny, personal walker) and the MT-AT (a spider-like, mountain-terrain walker). Hmmmm. Why wouldn't the Empire develop specialized walkers for specialized roles? And the first thing that came to mind was, essentially, a Battlemech.
Looking at the Imperial line-up, you have the AT-AT serving as a troop transport and assault vehicle. The AT-ST is a recon and raiding type. What they seemed to be lacking is a dedicated attack platform. It was something I initially termed an AT-AP (the AP standing for Assault Pod or Assault Platform). There were numerous battletech and robotech designs that could easily be adapted to Star Wars and fit this role. It was a fun mental exercise to be sure, but I never really included any of these thoughts into my campaign—mainly because I wasn't certain how it would impact the setting as a whole. Any time you introduce something new into a campaign, there is always the chance that it might unbalance things. What I didn't want to happen was to turn Star Wars into Battletech. In retrospect, though, I think I was just being paranoid. The prequel trilogy seems to have proven this—combat walkers of various types seem to fit just fine into the Star Wars galaxy. I mean, the clone troopers even had an 'Attack Pod' with a big gun on it.
And so in the Nagai War of my current campaign a new generation of combat mechs has taken the field. Quite appropriately, General Veers has taken command of the Empire's Walker forces, personally piloting a two-legged AT-AP in spearhead assaults against the Nagai ground forces. The Nagai themselves have a walker-like vehicle (based on a Robotech Zentraedi design) but the New Republic hasn't yet fielded any new Walker designs (though this may change in the near future).
One interesting twist to all of this is the character Fenn (now 'Mandalore'), who recently recovered a dozen ancient 'advanced' basilisk war droids from a hidden weapons cache. Since neither the player nor I liked the original design of the Basilisk (come on, it looked like a giant space shrimp), these advanced, quadruped designs are more 'panther' or 'dragon' like in appearance. They possess rudimentary droid intelligence (above animal level, but just below human) allowing them to operate independently of their riders or in tandem with them. Like the original basilisk, these droids are capable of space operations and even low-level flight, making them a versatile, mobile, armored addition to Mandalorian infantry.
And even with all of this? It still feels like Star Wars to me. Giant machines. War-robots. It works. Again, I am amazed at how inclusive Star Wars can be. But then again, I've been blessed with great players who seem to 'get it' and work /with/ me (usually) to keep game balance.