Fallout 3 is full blown addiction material. Just for example, I shall give you this series of incidents - I was on my way doing a main story quest - patching up a satellite tower for this revolutionary-type radio jockey and during one of my many wrong turns trying to find the Washington monument, where the satellite was located, I caught a random radio signal. Tuning in to that channel, turned out it was a distress call from some stranded scout mercenaries who were holed up on a hotel terrace, fending off waves of super mutants.
So, after doing my patchwork, I headed out in that general direction, only to come across another firefight between some other mercs and super mutants. Picking my way slowly through the battlefield (my specialty is sneaking), I looted all the corpses that were in safe reach. Looking up, I saw the Capitol Building was towering over me, so I took a chance and sneaked in. War was also being waged inside between mercs and muties, and it was easy enough for me to hang back as they thinned each other's ranks and then pick off the survivors with sneak critical kills. Got a ton of loot there, and I was easily lurking around that building for 2 hours in realtime, never bored a single moment.
Finally, I got back on track, found my way to the hotel, using a long section of underground metro tunnels first, exiting through a hospital next to the hotel and crossing to the hotel over a fallen radio tower that was straddling the two buildings. Cleared out the remaining supermutants in the area, rescued the team and when I visited them at their base later (a good distance away), they were grateful enough to gift me some kickass combat armor, a great upgrade from the glorified pajamas I'd been wearing up till then. Plus, I got a freelance mission from them to map out the Waste ruins, which basically means getting paid for each map marker I uncovered. Since I'd been a wanderlust-stricken vagrant so far, that resulted in a neat 960 caps right off the bat.
Another cool moment was how, after talking to a woman at some ramshackle outpost settlement, I got info about some potential locations of interest not too far away. Scouting them out, I nearly filled my pants after stumbling into a Deathclaw lair en route (this was fairly early in the game, absolutely no shot of surviving a head-on encounter with one), but had enough sense to sneak away and give it a wide berth from then on. Carrying on, it turns out one of the locations was an abandoned church, and sneaking around the side and through a hole in the wall, I found a solitary mark watching the window with a sniper and he was easy enough to take out when his guard was down. Thus, I acquired possession of the uber-satisfying Reservist's Rifle (that's the sniper, in case you were wondering) - one shot from this baby can take out even a minigun-wielding Supermutant Brute with a sneak critical headshot, if you're careful enough.
All these are just a fraction of the game. This mofo is huge. Some resized pictures I managed to take on the way:
