Mplath1: I'm familiar with Killer 7. It's certainly a trip but not quite what I'm talking about. Killer 7 is pretty wild from the first minute. I'm curious about games that sort of trick you into a lull of being normal before suddenly making you do a double take. I don't know that there are many games like this or if the medium is ideal for it. I guess something like P.T. fits a little bit. It's horror but that's beside the point. That same hallway starts doing some seriously strange things and that in itself is pretty unnerving. Subtle changes. Odd radio reports. Things moved a little or altered, sometimes in ways that you aren't positive you're just remembering wrong. There are some much more intense oddities too but I'm trying to focus less on the blatantly bizarre. Killer 7 is undeniably a trippy game but I think you see the difference of what I'm searching for.
In that case, Fallout: New Vegas comes to mind and not even for the option for in-world drug-use. If you chose the "Wild Wilderness" (memory on the name may be fuzzy) perk in character creation, it'll start with a pile of innocent red balls just sitting at the foot of a mountain. That's all I saw of it before I ditched the PS3 version, but it gets weirder and I have no idea if it's just wacky alternate skins or if game-play and/or story fallow suit.