I might be (and probably am) wrong here, but wouldn't that preclude anyone who isn't functioning in a contracted diplomatic capacity?
Definitely an example of what a small team can do, and I personally think the graphics are more then enough to not detract from the experience - dare I say nice enough to enhance it - but it is no Arkham Asylum, Crysis 5 or Modern Warfare 10. Which in a way, isn't a bad thing at all.
Also, nitpicking, but not open source
As for the toolchain? No - an interactive game requires far more tools, and more specialists to create. While animators and texture artists alone can create movies, you need high skill programmers in order to create a game. It is not as simple as just "putting an engine in". An engine is simply the backend classes, interfaces and methods to handle the resources, game logic and input in a structured way. You still need to craft the game itself around that, which requires, at the very least, competent programmers.
You also need competent designers. Not just for gameplay, but for stuff like HUDs, menus and other interfaces. Tool programmers, level designers, network specialists... You'll find that the amount of specialists required for interactive media is much greater then that of others.
Also, how are you going to convince a large enough group of people that your idea is the one? Unlike other projects, games don't serve a direct or obvious purpose apart from entertainment, so direction is something that is not as obvious. What sort of game would everyone want to see? Can the director get everyone to agree on an art/gameplay direction?
Sintel had paid artists, so in their case it was money. And don't expect a government grant enough to keep a much larger, more complex project going.
I don't even see why the open source community needs to compete with AAA games. More often then not, it is smaller budget games that actually innovate. Hell, most of the surprise hits of recent years have been from the indie community.
It would take a dedicated small team years of hours putting together something on the level of what I played.
The parent of my post did.
Yes, what you posted does look amazing, but it is a pre-rendered movie, not a game. So it's really apples and oranges. I don't mean to demean anyone making FOSS games, I just meant to point out that making a game that looks as good as new AAA games generally takes a sizeable, professional team working full time to accomplish.
When all else fails, read the instructions.