I really do hope the gameplay is different, but judging from the screens, it looks just like Fallout 3

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Ok, don't get me wrong, Fallout 3 is absolutely fantastic and is one of my favourite games of 2008. However, it began to grow a little boring after some 30-50 hours that I injected into the game. Some gameplay mechanics were a little tiresome after some time.
So I hope they can shift between mechanics, such as having a better variety, a larger variety of enemies and more excitement in its design. If New Vegas, which is a full game, is like Fallout 3, then I consider this purely DLC.