If one was to make a quick summation of Fallout 3 it would run along the lines of a pumped up Oblivion in a toxic wasteland with a 1950's futuristic spin on everything.
The Armchair Empire

The game could be categorized as a first-person shooter.
GameZone

Fallout 3 could be described as a first-person shooter...
Team XBOX

...first-person shooter vs. a top-down classic RPG.
Global Gaming

...first-person shooter quality action.
Twitch Guru

You can approach Fallout 3 as a completely straight-up, first-person shooter with RPG elements, if you want.
Gavin Carter

...you can play Fallout 3 as you would a twitch-based shooter...
UGO

Guns will be one of the major weapons in Fallout 3, and for the most part, the game will play much like a first-person shooter.
Games Are Fun

In fact, it looks an awful lot like Oblivion, only with guns. We can look forward to shooting off our very own personal Min Nukes in the fall of 2008.
XBOX365

Fallout 3 is ultimately an action role-playing game.
XBOXIC

It has all the makings of being the first solid bridge between the rapidly growing RPG genre and the immensely pop FPS category...
Game Revolution

I see this game as the spiritual successor to Elder Scrolls: Oblivion.
The BBPS

Comparisons to Oblivion are inevitable...
Joystiq

Fallout 3 is Oblivion on steroids. With nukes.
Bethesda newsletter, quoting Ten Ton Hammer

Fallout 3 feels like Oblivion for the rest of us, a game for people who are getting a bit tired of the same old fantasy fare.
Kotaku

The game is very similar to Oblivion...
GamerNode

If you want to compare Fallout 3 to another thing, then you will need to look at Oblivion.
Product Reviews

...it promises to marry everything you loved about Fallout with everything you loved about Oblivion.
Wired

Fans of the original Fallout may be understandably disappointed by the fact that the game has deviated so far from the original...
Gameworld Network

While some of the new additions may turn off fans of the original game, I for one am glad to see Bethesda is trying something different and updating the franchise for next-generation platforms. We already have Fallout and Fallout 2, so why not go in a different direction?
Twitch Guru

Change, in this case is good. It is, in fact, much like Oblivion meets Fallout.
The Escapist

Actually it's interesting for me - it harkens back for me to some of the most enjoyable first-person games I've ever played, the Terminator games Bethesda made. Fallout 3 is Bethesda's triumphant return to gunplay games, after swords and sorcery for so long. For me it's about bringing back THAT legacy.
Emil Pagliarulo, Eurogamer

Some people have guessed that Fallout 3 would be Oblivion with guns, and that is not the case. While it does use the Oblivion engine, never once did I see anything resembling Bruma or the Imperial City.
GiN

Fallout 3 won't be Fallout as you may know it...
GameSpot

If you are a fan who is adamantly against some significant changes to the way gameplay occurs in the Fallout series, I'm going to tell you right now and save you the disappointment: I don't think you'll like Fallout 3.
Game Informer​

..don't be shocked if the game ends up being the best of the series.
Vodoo Extreme​