Re: Fallout 3 / Oblivion with Guns
To me, it's Fallout just because it follows the same background plot. It feels like Terminator Salvation compared to Terminator 1 (not in terms of quality, but in terms of style).
It's unlike Oblivion in that Fallout has a proper experience counter, in which you kill things to fill your experience, then upgrade your skills. Where in Oblivion (In something they've done in the Elder Scrolls since Dagger Fall, more than likely Arena as well) you have to use the skills to upgrade the skills, and upgrade the skills enough you can level up to increase your stats, which to me makes more sense than "Hey look I just gunned down a bunch of raiders with a pistol and I leveled up. I am now better with first aid."
In Oblivion you can also join factions. The Mages Guild, Fighter's Guild, Dark Brotherhood, and so on and so forth. In Fallout 3 you do not actually join any factions, or even get any true advantages for helping any of them. Even helping out the Brotherhood of Steel isn't an advantage as its just how the plot goes.
As for the environment, Oblivion wasn't copy and pasted Cappy, they designed the map from scratch. Neither was Morrowind. They've done the same process of map design since Elder Scrolls 3, and used it in Fallout 3 to create a world worth exploring. The big difference is that Oblivion has green, with fields, castles, villages, clear blue lakes, demented blood caked realms of Oblivion, the strange islands of the Shivering Isles, and a fight above the clouds, whereas Fallout 3 has plains of sand covered in weeds, ruined buildings, husks of old technology scraped together into villages, poisoned rivers, twisted fleshless characters and so forth.
Even down to Combat, there's no fatigue to come into play to determine your damage, but they do have a V.A.T.S. system which allows one to pause the game, take a breath and determine where they want to shoot their enemy.
Yes its easy to call Fallout 3 "Oblivion with guns" but if that was the case I suppose Dragon Age is KOTOR with swords. Battlefield BC2 is Call of Duty with vehicles. SoulCalibur 4 is Tekken with weapons. Mortal Kombat is Street Fighter with blood. The Darkness is Chronicles of Riddick with Demons.