Better still are the odd little vignettes and ambient stories written into the landscape. There's nothing more amusing than creeping into a derelict hotel room only to discover that some previous occupant has left a teddy bear and toy dinosaur arranged with some kitchen implements to create a Toytown knife fight.
Make no mistake, this is a massive game. The map feels more populated and varied than Fallout 3's, from the scrubland frontier villages, through aspirational small towns like Freeside, to the Strip itself, where a tatty semblance of normality has taken hold with neon signs, almost-clean casinos and untainted food and water.
You'll be meeting lots of different factions as you traverse this world and the game's new focus on reputation makes them more than a pointless palette-swap. You'll be doing missions for most of these groups at some point, often bringing you into conflict with others, and juggling your allegiance is trickier than it seems, especially where the main quest line is concerned. There are multiple forces vying for control of New Vegas and sooner or later you need to pin your flag to somebody's post.
There are the dubious crime families of the Strip Omerta, White Glove Society, The Chairmen and the militaristic forces that aim to rein them in: the New California Republic Rangers, Caesar's Legion and even the Brotherhood of Steel, diminished by time but still a powerful presence. Further down the food chain are rough and ready gangs and cliques, charitable groups and traders. The ghouls have found religion. The Super Mutants have their own talk radio station. Progress is on the march.
Lording over all of it is the mysterious and reclusive Mr House, New Vegas' default ruler, whose inscrutable plans dragged you into this power struggle in the first place. Post-BioShock, we've perhaps met one too many toffee-voiced videogame oligarchs ordering us about from afar. But New Vegas just about makes it work, if only because your freedom to ignore or defy the man at the top is unlimited by the linear narratives of first-person shooter design.
Indeed, Fallout remains a procrastinator's dream. My idealistic intention was to plough through the main quests and then explore the margins until my deadline loomed. 50 game-clock hours and 38 quests later, I'd barely scratched the surface of the story, having spent my time being wonderfully distracted by interesting structures and enjoyable side-quests and ooh, what's that over there, let's go and see. I'd visited just under half the locations on the map, was two-thirds of my way towards the Level 30 cap and, according to the Achievements list, there were still at least 16 major quests to be completed. So, yeah: big.
It's all incredibly intuitive if you played Fallout 3 since, on the surface, New Vegas looks, sounds and plays exactly the same. With only a few new creatures and a lot of familiar scenery items, it's initially easy to think of it as a really big expansion pack rather than a game in its own right.
There's more going than just reshuffled assets, though. Obsidian has reintroduced more RPG features, such as crafting. You could make a small selection of weapons in the last game, but that's changed now. You can still create some explosive devices at workbenches, but mostly you'll be putting together your own stimpacks and medical supplies. Camp fires allow you to take the raw ingredients found around the place and turn them into nutritious, stat-boosting meals, while you can even salvage, recycle and repack your ammo supply. Though the world may be crawling back towards civilisation, you'll be living off your wits a lot more.