An excellent game made better by a talented modding community
Fallout 3 is a action RPG set a 1950's version of a post apocalyptic future, you play someone who was bought up in a vault built a few a hunderd years ago to protect people from the nuclear war. Before I go any further it's worth mentioning that even though the title suggests it's a sequel it is not anything like its predecessors and should be judged as a game in it's own right.
Bethesda seem to have learnt from some of the criticism they received from Oblivion, there is less hand holding in Fallout 3 and now the player has choices and is also allowed to fail.
Graphically it's doesn't look too bad and on the PC but it's easy enough to improve the visuals with new textures and other mods. As with many other games once again they've overdone the HDR, shame as a more subtle use of the effect would have looked far better.
The gameworld itself is quite large and your free to go where you like from the start, this also means that if you stray into the wrong place at a low level your only choice is run like hell or die, a refreshing change from Bethesdas last game. The gameworld itself requires the player to ignore a lot of things that make no sense at all, it never rains and yet there are puddles, people are eating food that is 200 years old, there is very little plant life and yet we know from experience with Chernobyl that nature returns very quickly once humans are out of the way. The story also has a few plot holes including one glaring one at the end. NPCs don't do very much either, yes they eat and sleep but otherwise just tend to wonder around looking bored. It's also worth mentioning that some of the dialogue is nothing short of terrible, writing is not Bethesdas strong point and it really shows in this game. That said the gameworld is still very good and has an excellent artistic style.
Although the game looks like a FPS and can be played as one your skills with various classes of weapons do make a difference, as does the condition of them. The game also has more RPG like VATS mode that pauses the action allowing the player the select enemies or parts of said enemies, this uses action points that regenerate over time.
The great thing about this game is mods, the mods available for this game are amazing. Just about anything you don't like can be altered in the same easy way they could be with Morrowind and Oblivion. The game uses a plugin system that drastically lowers the chance of permanently damaging your game with any mods. Bodies, clothes, armour, weapons and just about anything can be replaced with mods, this really does increase the replay value.
I would certainly recommend the PC version of this game to others, the mods alone make it worth the money. Be sure to patch it though, Bethesda are not known for great quality control.