I ended up getting Rage. At least after spending $50 for Future Soldier and $30 for Rage, I at least end up with one game to play.
Rage is like Fallout 3 but with less story, more firepower, and better graphics. The engine isn't as good as I hoped because the environment isn't distructable and I always feel "stuck" in the canyons. It also seems to be "daytime" ALL the time. No one sleeps and no night time stealthy moves. Anyway, I just started the game and it's at least worth playing.
I expect to get Arma II with DayZ and maybe get Arma III later..
It seems to be getting harder to find mature sandbox FPS..