It's based on the Gamebryo engine which the newer Fallout: New Vegas game also uses.
I bought Fallout 3 in 2009 after all the DLC came out on the Xbox 360 and spent many hours walking the wasteland with my faithful pet 'Dogmeat', I even got all the DLC.
Now I went everywhere and explored everything I could find before even starting the DLC. Unfortunately before I could start it my save corrupted and all of those hours turned to dust.... Never played the game again as I was too gutted.
I have been licking my wounds since that day but still enjoy the game itself so when Steam had the 'Game of the year edition' on for a crazy discount I whipped it up and added it to my 'To be played list'
We started talking about Fallout 3 at work last week so it felt like a good time to get back into it and heal some old wounds and I am looking forward to getting 'Dogmeat' back as he is miles better behaved than my real life animal friend 'Bad Dog'.
The next thing was the starting stats for my vault dweller, in the long run it makes little difference what you choice but it affects your starting experience massively and I had to make sure I had at least 30 points in explosives and 30 in repair so that I could finish two quests in Megaton and finish the 3rd quest to get my house.
After 6 rerolls that spanned the weekend I finally settled on the following:
I finally finished the quests in Megaton and set out in to the wasteland. The thing I like about this game is the same thing I like about Skyrim and that is its just huge, you can spend 3 hours in game and not even touch a main quest, just explore and see the sights and take in some of the random events that happen along the way.
If you have been trapped in a vault for the last 5 years and not played this I would give it a go as the whole game including all the DLC is £14.99 for the Game of the year edition on steam.