Because it makes no sense to employ level designers, artists, etc. to sit on their hands all day.
For all Valve is diversifying, they still have a large number of people on board who are really good at making games. Having them not make games would be crazy.
If this isn't the prototype of a forum system to replace the vB Steam Forums, I'll be very surprised; far too much implementation necessary there for this to be Steam Workshop only.
It's called Courgette, and it is indeed pretty awesome.
http://dev.chromium.org/developers/design-documents/software-updates-courgette
Doesn't need source code, though; it works by doing a disassembly of the compiled executable. It'd be a smart idea if Valve incorporated this algorithm, as it...
Worst case scenario, I imagine, is Valve give Australia the neutered version they normally give Germany.
I don't know what changes they make to L4D, but I know in TF2 they have things like the blood is turned black, gibs become random objects like springs, rubber ducks, etc.
I'd use the incredible benefits of time-travel computation (see http://www.frc.ri.cmu.edu/~hpm/project.archive/general.articles/1991/TempComp.html) to build myself the world's best gaming computer, and use it to play L4D, L4D2, TF2 and Episode 3 at absurdly high framerates.
Have to say I'm glad they've made that change. If the melee weapon replaces your standard weapon, it just places them into the penalty box rather than the fun box.
I imagine they'll let you swing at zombies' legs with the melee weapon. Maybe. The incapped pistol was always hilariously...
TrueSkill is really interesting, as it turns out. It came out of Microsoft Research, and it's actually better than something like ELO. It keeps track of both how good it thinks you are, and the level of uncertainty it has about your skill.
When you start, it's very uncertain about your skill...
It's interesting how they're trying to turn game design into an exact science, and apparently succeeding.
The scary thing is that no doubt L4D is generating huge amounts of statistical data that Valve is using to monitor how the game is actually playing out there in the real world.
I...
I have to say though, the boss infected AI is pretty damn good. They do a good job of really screwing you up sometimes - I have to say I'm looking forward to getting to play as them!
Depending on what retail product you buy, there will be different sized updates required.
Buying the Orange Box, you'd need no updates for HL2 at all, and probably not for Episode One either.
Episode Two and Portal would need some fairly small engine updates, and TF2 would need pretty huge...