Re: Isn't it really hinted at in previous Fallouts?
While I do not like the fact that Bethesda have made aliens a big part of the Fallout plot (having a DLC based around them is absurd, and the alien ship and blaster in the vanilla game were already questionable decisions), I would like to defend the actual existance of aliens in the Fallout universe as being canonical.
In Fallout 1 the special encounter isn't the only place you see aliens - I recall an alien body in some kind of suspension tube thing in one of the levels of The Glow. Now, you can call that an easter egg as well, but the fact is that's TWO alien easter eggs in Fallout 1, one of which can be seen by anybody by visiting a location, no high luck encounter required.
Also, one of the random generic messages that Brotherhood Scribes can say in Fallout 1 is "I've seen an alien space ship before."
Also, the "alien" page on The Vault mentions something about the Shi in Fallout 2 having some knowledge of aliens?
http://fallout.wikia.com/wiki/Alien The citation thing links to the Emperor computer's message file but I see nothing about aliens in it, so I'm not sure where that comes from.
There's also the fact that the Fallout 1 alien encounter is a far more singnificant and important special encounter than the others. The others, you just see Godzilla's footprint, or see the TARDIS for a couple of seconds before it vanishes, leaving behind generic items that are useful but not super special or one-of-a-kind (such as a stealth boy, motion sensor, geiger counter etc). You forget about it a few minutes later. You may use the resulting useful item at a certain point in the game, but it isn't a big part of your experience.
By contrast, the alien encounter gives you the Alien Blaster, one of the most powerful weapons in the game. It has its own unique appearence, based on classic sci-fi but not particularly based on any movie or TV show (unlike the Doctor Who/Star Trek/Godzilla stuff). The Fallout developers designed their own alien blaster with unique appearence and properties and its own item description. It has its own special awesome unique death animation (no pulse weapons in Fallout 1, rememember!), and it uses a common inexpensive ammo type.
This means that if you get the alien encounter, you are likely to use the alien blaster throughout the rest of the game, for all close-range combat. If you are lucky and get the alien encounter early in the game, you're going to start boosting up that Energy Weapon skill straight away, just for the alien blaster, rather than boosting it up for the plasma rifle later. It's hard to call it an "easter egg" when you've used it to disintergrate a third of the mutants and purple-robed people in the military base and cathedral, and zapped the Master's Lieutenant in the face with it.
If Fallout 2's Holy Hand Grenade encounter worked correctly, you could simply dismiss it as an easter egg, cause it is a one-shot superweapon, and the whole scenario is obviously a reference to a popular film. By contrast, the alien blaster is a primary weapon you'll use throught the whole game.
That's possibly why they ended up cutting out the Phaser from the star trek special encounter in Fallout 2. If it gave you a useful weapon that you could use throughout the rest of the game then the player would be constantly be reminded of the encounter, making it less of an easter egg. They decided it was OK for you to get some extra-good stimpacks (hyposprays) that you would use a couple of times, but having you vaporising the Enclave and Frank Horrigan with a Star Trek phaser would be a bit too much.
There's also the fact that the alien blaster reoccurs in Fallout 2 in an encounter with a trader named Willy, who also has a bunch of guards armed with rare 9mm Mauser pistols. He's always in the same area of the map, north of Modoc (which makes sense, it's a trading post and there are a bunch of traders that stay in the Bed and Breakfast). When you encounter him his inventory depends on your level and your luck. He talks and talks and puts you to sleep and when you wake up you dont know what he is selling. If you are over level 13 and pass a luck check then he has alien blasters. You can kill him and get yourself several alien blasters! Alien blasters to spare, to give to your NPC companions or sell in shops! And the thing is this guy can't be considered just an easter egg, anyone that walks on that bit of the map (north of vault city?) is likely to encounter him, and you can visit him repeatedly to try your luck again.
So, let's do the full run-down of alien related things in Fallout 1 and 2:
1) The crashed alien ship in Fallout 1, obviously
2) The alien blaster you get from this encounter, one of the best weapons in the game, which has its own proper item description, and which you can continue to use throughout the game
3) Alien corpse in The Glow
4) Brotherhood Scribe can randomly mention having seen an alien space ship
5) Skynet in the Sierra Army Depot in Fallout 2 mentions being made with alien technology. (Is he reliable? Does the fact that he has a few dates wrong make him unreliable? More like unreliable developers doing inconsistant dates when writing the script.)
6) Merchant encounter lets you get several alien blasters.
7) For years many people thought of the Wanamingoes as being aliens, and there are Fallout 2 walkthroughs that call them aliens. The Fallout Bible set the record genetic experiments, but the Fallout Bible is an after-the-fact document written by one Fallout developer, and only hardcore Fallout fans have read it. The average normal person that played Fallout 2 a few times and chatted about it with mates is likely to have thought of them as aliens.
I think that with all that, it is quite reasonable for the prescence of aliens to be canonical rather than merely an easter egg. But, the point is that even though they are canonical, they are not supposed to be a big part of the Fallout universe. It's also a canonical fact that the USSR was still around during the war, and that the war was between the US and communist China, but that doesn't mean an adventure set in the post-apocalyptic remains of Russia or China are a good idea.
Still, I expect I will enjoy this DLC, since I'm a big fan of stuff like "Mars Attacks!" I don't personally think having Mars Attacks style stuff is very Fallout-ish, but then to enjoy Fallout 3 you've got to forget about Fallout heritage anyway. I enjoy Fallout 3 as a generic science fiction game with retro elements. So this DLC is right up my street.
Sander said:
Furthermore, the theme of alien abductions wasn't a '50s thing - it is mostly an '80s thing.
There was a little bit of abduction stuff in the 50s, and there was quite a bit of abduction stuff in the 60s. The 60s had stuff like "project bluebird", US Air Force investigations into all the stories of UFOs, some of which included abductions. The "men in black", supposed government agents that would threaten people that had alien encounters, were mentioned in a book in a book on UFOs in 1954.
In the 90s there was a men in black style TV series set in the 60s where many of the episodes were based on outlandish alien abduction stories.
I recall a great 1950s sci-fi movie in which a little boy sees a flying saucer lands in some sandpits in the countryside. Then his dad starts acting strangely, and insists that his wife go out on a walk with him. Turns out that the aliens are abducting people that walk on the sand. Then later they send them back with mind-control chips or something to do their bidding, and lead other people to the sand pits to be abducted.
There was also the 1960s TV series The Invaders. Several episodes dealt with people being abducted. (And the aliens themselves were always in fake human forms, often in important positions and sometimes in the government or military, so presumably they often abducted/killed someone and then replaced that person.)
So yeah, alien abduction didn't become a massive phenomona until the 80s, but there were certainly stories of it happening in popular culture long before then. The first stories of people being "anal probed" and all that stuff was from the 1950s.