Wuzzat about the Big Empty and Tibbets?
Anyway, someone asked how combat based this is. It's really difficult combat wise, so it's preferable to sneak. Ghost People have hard hitting weapons and Security Holograms are invincible due to being just light and can only be turned off by hacking security terminals or smashing an emitter.
The Cloud, that reddish stuff you see everywhere, is poisonous and takes health over time. Cloud residue makes deadly poison, Nightvision, and a awesome but addictive martini. Another enviromental obstacle is that the radios and speakers around the Sierra Madre, due to being in decay for so long, now emit a frequency almost exactly like the one Elijah uses to make your collar explode. So you have to turn off or smash speakers before the collar detonates. There's also conventional traps everywhere.
Each companion has their own perk that deals with each of these threats. Dog will finish Ghost People for you, God makes traps not trigger, Christine can block radio signals for a time, and Dean can block the Cloud from hurting you for a time.