I'm running a Gamma World campaign set in the Deadly Waters Ocean, which is so vast and desolate that the survivors believe the world is submerged entirely. Not true, but that's aside the point.
Recent scavenger groups have been diving for Ancient Junk, and some have discovered a deep underwater facility that stores ancient machines. Mechs! More and more of these ancient mechs are being found, creating a new face of survival on the Deadly Waters.
So, all that fluff aside; I have been thinking of ways to include mechs and mech battles between dungeons. When the PCs go into caves, or Bio Shock cities, they need to dismount to continue. So they will not be replacing their PCs, just using a utility battle vehicle between point A and B.
My question is how I should handle this. I'm personally cool with mega damage. They'll be fighting other mechs, krakens, zombie whales, and all sorts of One Piece-esque sea monsters.
My first instinct was to give each mech three Origins; Android, Giant, and X. X would either be rolled for or picked from the PC's two Origins. The mech abilities would either be removed in lue of weapons or Omega Tech upgrades, or kept in addition to weapons and omega tech.
There could be a shop/onboard mechanic for the mechs that requires Junk, or credits to upgrade.
When it comes to combat, every equation that has a '+' in it would change to 'x', giving way for that mega damage. Mechs would obviously have HP to handle this. So where to cripple the players? Give them fuel costs per move. Quick Attack would give back 2 Fuel, Power Attack would return 1 Fuel; ammo and skills would deplete x amounts of Fuel, and there would be a skip turn ability to regain 5 Fuel.
So, like the title says: Xenogears.
Thoughts? Ideas? Improvements? Doubts? Let me know. I have no one to talk to about this, outside my players (who are better not knowing until it comes up as a surprise?).