Exotic Environments

Many mecha battles take place in unusual environments. Here are some rules for those situations.

Space
Sea of stars, the cold void, final frontier. It's mostly a heck lot of empty. Which really saves up costs when it comes to making backgrounds and also means you need to worry a lot less about making sure your stuff remains in a constant scale.
 * There is no air to breathe, you can only hold your breathe for half the time, and all DCs to do so are increased by 20.
 * Unless properly protected by a mecha or space suit, creatures take 1d12 cold (if in shadow) or fire (if exposed to a star close enough to provide daylight) damage every round while in the void of space. DM may adjudicate those values depending on how far/close you are to a source of heat.
 * Pilots inside mechas can still use the Listen skill, representing “hearing” for radiation.
 * Any special senses/radars granted by Arsenal Options/Super Pilot upgrades/Einst/Peace Princess/Support Staff work in space, otherwise they don't. No exceptions allowed, no matter how specific.
 * Any effects that would make you fall to the ground make you fall towards the closest object at least three size categories bigger than yourself instead.
 * Being tripped means you're left spinning in place and need to spend a move action that provokes attacks of opportunity to stabilize yourself before you can move again.

Disclaimer About Realism
In space there is no atmosphere and "weightlessness" changes one's relationship with gravity. However, pretty much every action show/game doesn't care about that. You can hear lasers and explosions, while having your engine turned on at the same potency simply results in constant velocity and you need to turn on the turbo to go faster and when you turn off said turbo you lose speed despite no atmosphere to slow you down. That's even more true in SRWd20 games where Evangelions can just run in space and martial art robots can slam you against the void and don't care about the whole virtually zero weight factor. Plus the purpose of SRW d20 is having mecha fun and not to be a physics simulator. Think of the catgirls. If a player at your table complains, just say it's because of magic/extremely advanced SCIENCE!