I'm sure the idea has been pitched but not that I've seen.
It would be the actual Hunger Games, none of the love triangle stuff from the books. But it’s NOT based on the book. There is no Katniss, no Peeta, etc. You create your own character(s). I'm thinking it would be multiplayer only, as in you against 23 other players. Not even thinking of a single player version.
There would be some character customization in the sense that you select which district your character is from and that gives an inherent bonus (District 4 = bonus to fishing, District 11 = bonus to plant knowledge, etc). It also determines what weapon you should use, but you can really use anything you want or find. There is no guarantee that your weapon of choice will be available and there is no guarantee that your district abilities will help. There are also other skills that are common to all districts such as stamina, swimming, climbing, etc. You could invest all points into speed but you'd be terrible at everything else… and most likely die.
Just like the books the best weapons and supplies can be found in the cornucopia. If you don’t want to risk getting a good weapon, a knife can be obtained which is the “basic” weapon. The knife is somewhat close to the cornucopia meaning you’ll still have to run for it but you won’t be in danger of players with swords or spears immediately. Any player you kill drops their whole inventory and you can loot them if you want (and you should).
Since the books emphasize districts 1, 2, and 4 as the "career" districts there would be indeed be higher buffs but higher penalties associated with these districts in order to even out. Fragile alliances will be formed and broken, keeping you on your toes all the time.
OR there could be a "Careers" mode where the lobby would randomly assign 6 out of the 24 players as the careers districts who initially are on a "team" (no friendly fire for a certain period of time) promoting them to kill as many other tributes as possible before the friendly fire takes effect. Even after friendly fire is enabled, it may be beneficial to maintain the alliance.
The Games are about survival and making sure you've got water and food is just as important. To ensure that the match isn't a bloodpath and is played tactically, tributes grow hungry or thirsty and lack of food or water will result in starvation or dehydration respectively. Like Careers mode this would probably be ON in one playlist and OFF in another playlist, allowing for the "true" Hunger Games experience and a fast-paced experience (for the CoD crowd).
There would also be “in-game achievements” not like actual achievements. These in-game achievements would earn you gifts from sponsors. For example, the first tribute to draw blood will receive a gift from a sponsor a little later on (if the tribute dies before receiving the gift… too bad!).
Maybe the engine can generate a new map with different environments each match making the map always different. Of course, originality would run its course but there would be a huge variety in maps and environments.
I'm just drooling thinking about this while I type this. I’d definitely buy this.
That's a very easy problem to fix. Don't include ages in-game and don't have character models vary like crazy in height. They can be seen as young adults. It doesn't follow the books exactly like I said, the tributes can be older.