My idea
It should be a Downloadable title. Multiplayer only. YOu can customize your character. There are Different classes, which help determine what weapons you are proficient with (you can use any weapon. Proficiency increases damage when using those weapons.). Your District of Birth give stats boosts and unique abilities. Friends can go into non-ranked matches as "Sponsors" and drop power ups, however anyone can use them. Once you die, you can play as a Game-Maker, and unleash traps (again, only on non-ranked matches). The damage system has you healing only by applying the medical care, fused a Fallout 3 like limb damage thing. Infections and crippling from MGS3 included.
The game will have twelve different maps.
Generic Forrest
Generic Snow
Wasteland (Only area with modern weapons)
Super pretty zone (Where nearly everything kills you, see Catching Fire)
High Mountain (Lots of cliffs, rather dry, large wind effects.)
Large plains (Some mines stay on, doing a crap ton of damage.
The Clock Thing (from Catching Fire)
Flooded place (Lots of Water, but very little is actually drinkable)
The Underground (Dark very often. Torches can be found in hidden spots)
Scorched plains (Plains with a mixed layout, lots of fire)
The suburban area (A 50's suburban neighborhood)
Something else I have not thought of.