Most of those can be seen as true though.

Skyrim would have infinite quests

This is sort of true in a way; the game does technically have infinite quests though they are usually small fetch type quests that are forgettable.

"You can climb that mountain"

Is this even a real lie even at first glance? Anyone who's ever played an Elder Scrolls game since Morrowind knows you can jump your way up any steep landmass.

That in Skyrim settlements or towns could be wiped out if the player chooses to kill everybody.

I guess you can count this one as a lie since you can't kill everyone in the game like you could in Morrowind without mods or console commands, but if you could it'd just be a matter of what your definition of wiping a town out is.

That Radiant AI was organic behavior and that the things they did were not scripted.

I guess this one is safe to pass off as a lie but I don't know who'd believe it anyways, every AI ever created is scripted to some extent.

Fallout 3 would have over 200 endings.

Okay this is probably the biggest lie I've heard him say, and I actually think it would have been the worst decision they could have made if it turned out to be true. Would you rather have a few decent endings or a couple hundred horrible endings?