Valve has no formal management or hierarchy at all.
Now, I can tell you that, deep down, you don’t really believe that last sentence. I certainly didn’t when I first heard it. How could a 300-person company not have any formal management? My observation is that it takes new hires about six months before they fully accept that no one is going to tell them what to do, that no manager is going to give them a review, that there is no such thing as a promotion or a job title or even a fixed role (although there are generous raises and bonuses based on value to the company, as assessed by peers). That it is their responsibility, and theirs alone, to allocate the most valuable resource in the company – their time – by figuring out what it is that they can do that is most valuable for the company, and then to go do it. That if they decide that they should be doing something different, there’s no manager to convince to let them go; they just move their desk to the new group (the desks are on wheels, with computers attached) and start in on the new thing. (Obviously they should choose a good point at which to do this, and coordinate with both groups, but that’s common sense, not a rule, and isn’t enforced in any way.) That everyone on a project team is an individual contributor, doing coding, artwork, level design, music, and so on, including the leads; there is no such thing as a pure management or architect or designer role. That any part of the company can change direction instantly at any time, because there are no managers to cling to their people and their territory, no reorgs to plan, no budgets to work around. That there are things that Gabe badly wants the company to do that aren’t happening, because no one has signed up to do them.