OK the title is a little vague on purpose. Here's my thought with a little background on the idea.
When I play campaign games, I want to win. But I don't want it to be too easy. I want a challenge. But I don't want a challenge that makes it boring- like you have to wait behind cover, shoot, get back, etc. That's boring. So how do we make it so it's not too hard, but beatable? I propose a thing I'm gonna call Shadow Mode for now, for lack for a better name.
Say I play campaign on Normal. I'm in the middle of a fight. I lose about 2/5ths of my health. A little reminder in the corner pops up. It's the Legendary Symbol. This symbol would indicate that if you were playing on that difficulty, the damage you've taken would kill you. When you take some more damage, the 'Heroic' Symbol pops up in the corner. If you were playing on Heroic, you'd be dead.
I think this is a tool that would make the game more interesting. When you see that symbol, you know that you would have needed to be more careful. You can quickly get back behind cover. Be more cautious. Adopt a different strategy. It could help add variety to the game.
The only thing I see that may cause an issue is in the AI itself. When on a higher difficulty, the AI acts different. That can't be helped. Still, a little addition like that might be useful. I personally like this because I figure if I want to play on an easier difficulty but I want a challenge, when I see that symbol I know to get back quick. Even though I would be dead by then, it is a way to get accustomed to that. style of play.
It's something very small that would be easy to implement from my understanding. I just thought I'd throw the idea out there- get some thoughts on it. I only thought of it a few minutes ago so there could be improvements most probably. Anywho:
Discuss.