I have been throwing around some interesting ideas with the other 2 non-dev members of my team and getting their feedback.
So far here is the list we have come up with:
Upgradeable HEV Suit:
On certain objectives (secondary and special) you will have an opportunity to collect parts from completing them. These parts can be traded in at terminals found throughout the game to upgrade your HEV suit.
Upgrades would include slight armor increases, max hp and power increases in increments of 5 points.
Upgradeable Weapons:
At these terminals you can also tweak your weapons with parts. You can increase the damage slightly or increase the max amount of primary or secondary ammo that the weapons can hold, and increase the clip size.
granted these are just ideas, I am no where near sure where to begin to accomplish these but from ideas come life so I am sure that applies to coding somehow.
Updates to the above ideas:
So I was thinking it over the other day and thought how unbalanced it might make the game.
So these parts will only be attainable from Special missions, and not from secondary.
There will be at max 2 special objectives in each chapter (most of them will only have one).
This means that there will only be at max 14 of these items to recover (assuming that all chapters have 2 spec missions and that we only have 7 chapters).
In reality though there is likely to be only 8 such missions (2 would be in the largest map we have planed a the moment, City 25).
I have not decided yet if I want to keep the +5 per part, or make some for of escalation on it where after three _+5's it takes 2 parts to add another +5 (this would be to health and power only).
have not decided the denominations for weaponry ups yet.