There's one thing I've been wondering about that would be a major change to the game as it stands.

This is mainly aimed at people who have read the playtest draft (http://genericgames.co.nz/downloads/Badass_Space_Marines_draft_1.pdf). But it's basically Aliens: the game, with shared narration of colour (so that you can be fighting any kind of bizarre creatures, depending on how it runs).

Currently the rules say that when the GM allocates damage from the aliens, they get to just put it on any marine they want. So they can kill extras or player marines, basically whatever seems like it will be more tense and scary. Marine players have no way to defend themselves - if the GM has the rolls and decides to kill your guy, that's it for them.

Now, this is on purpose. I wanted to make it so that nobody can ever count on "their guy" being the one who survives to the end. Also, the way the GM allocates damage each combat round has other implications on the pacing of the game (i.e. you can make things easier or harder on the marines by how you do this, and thus control game length and tension).

But I keep thinking that sometimes players will get some cool ideas about the essentially disposable marine they are playing and want to keep them around. But then I'm not sure if that detracts from the basic concept too much.

Mechanically, I think it would be easy to add the option. Just let the marine player spend Fuel points (that means sacrifice effectiveness in later combats) to reduce damage. And they'll also forfeit the Fuel they would otherwise gain from taking a hit. Indeed, I could also allow them to defend other members of the squad in the same way.

So, the question is:
1. Should I allow marine players a way to avoid being killed whenever the GM can and wants to waste your marine? Is giving players a temptation to sacrifice their effectiveness too mean? Is it too mean to just kill the character whenever, even if the player is grooving on the way they are playing the guy?
and
1a. If so, maybe let people defend other marines in the squad as well? Or maybe only other people (i.e. sacrifice yourself for them)?

Your solution (spend Fuel) is exactly what I came up with.
It seems reasonable.

All it would do really is forestall dying for one round of attacks, right? So the player's really making a choice between hanging on to a character they love for a moment longer in order to do something cool vs. taking the hit & gaining effectiveness with a new, featureless marine.
I like that. There are times I would've done that in the playtest.

Currently, marines are very disposable.
It would do something interesting if you could use a combination of your own Fuel & Fuel given to you by other players to defend yourself.
There are times I would've offered Fuel to another player in the playtest.

Is it a set number of Fuel points to avoid an attack or would you reduce damage on a 1-to-1 basis?

Thanks for the input, hix. That "I would have done it in playtest" is perhaps the key point there.

In terms of "how much Fuel to defend", I'm not sure yet. It would probably be one for one but that would need to be tried in play.

I also plan to add GM advice to the effect that "if someone has spent Fuel to defend themselves, check with the player how long they want to keep the marine on". It's a pretty big flag that the guy should stay alive, really. And making a player repeatedly spend Fuel to defend would be nasty - it might doom the whole team.

I'll consider options on the "spend Fuel to defend others" option. That one actually adds more to the game, in my opinion. It's one thing to value your own guy enough to sacrifice effectiveness, quite another thing to do it for someone else.