As I've said before, I have a strong interest in running Mekton Z right now, but not necessary as-is. The publication date on my copy of Mekton Z says 1995, and while I don't think it's necessary to rewrite all or even most of either that or MZ+, I think it's safe to say that after 12 years, a few improvements can be made. Although the changes I have in mind need to covered individually, I'd like start with an overview:
Character Creation - To be blunt, I plan to dump Mekton's older Interlock mechanics for characters with Talsorian's more recent Fuzion system. Fuzion was created as a hybrid of concepts from the Interlock and Hero systems to produce a streamlined method of character creation that could be adapted to games with more detailed genre-specific rules (powers in Champions, mecha in Mekton, cybernetics in Cyberpunk). Unfortunately Fuzion ended up as staid as older monolothic systems, with the Fuzion-based Talsorian* games Bubblegum Crisis and VOTOMS adapting a few elements from Mekton but still being largely based on the Champions-based "Primary" Fuzion rules used in Champions: The New Millenium. Character creation is the only real weak point of Mekton Z, the rules for mecha creation and combat work just fine.
*I don't want to bad-mouth Mike Pondsmith or R.Talsorian Games, but I will criticize them.
MV, MR, and Actions - One element of "Primary Fuzion" I do want to incorporate is the Champions-style method of handling the number of actions a character can take each round, and the Manuever Value for mecha. Basically, I want to set up a mechanic where characters have a score determining how many actions they can take per round (1-10), modified by the weight-based Manuever Value of the mecha they're piloting. Bigger or less powerful mecha are allowed fewer actions, smaller or more powerful mecha are allowed more.
Legs - As an open, somewhat subjective effect-based system, the genre conventions that inspired Mekton can sometimes be forgotten in the mecha designs of ambitious players. As strange at it may seem, one aspect of the Mekton Technical System that seems to suffer the most from confusing Japanese and Western perpectives of mecha is the simple fact that they have legs. If you look too closely, legs on giant robots can seem pretty silly, especially since so many mecha can fly, but they're an important part of seeing the robot as extension of the character instead of just the vehicle they happen to be operating. I've seen a lot of skeptical players either avoid legs entirely (unusual in iconic mecha), or stuff as many weapons as possible into them (also unusual).
The simplest solution to this seems to be to go to the "servos' section of the MTS and just rewrite legs so that they A: have little or no internal space for mounting weapons and B: are cheaper for the lack of space. Unfortunately changing one aspect of Mekton mecha construction is like eating one potato chip, and with the flexibility of the construction rules changing the basic stats for legs won't matter much if you can't discourage players from just choosing to sacrifice all the kills (structural integrity) of each leg to hollow them out for weapons.
Multiplier Systems - Last and least is my interest in updating mecha "forms" and other multiplier systems, not unfairly often seen as a somewhat "handwavy" aspect of the otherwise straightforward MTS. To be honest, I'm not sure I could really improve on them in general, and I certainly can't beat the thorough analysis Jonathan Lang has already put into the transformation rules.
