Portal 2 developer and Steam owner Valve has criticised Microsoft's update system for Xbox 360 games.
Senior Valve staff admitted the "total failure" of updates for multiplayer shooter Team Fortress 2 on 360 to PC Gamer, but laid the blame at Microsoft's feet.
"We thought that there would be something that would emerge," said CEO Gabe Newell of Microsoft's update restrictions, "because we figured it was a sort of untenable... 'Oh yeah, we understand that these are the rules now, but it's such a train wreck that something will have to change.'"
Added lead designer Erik Johnson, "TF2 on the PC side has delivered a huge amount of value, but we've screwed up on the other side."
The Left 4 Dead developer was far more positive about PlayStation 3, following its surprise return to the Sony fold at this year's E3.
"That's why we're really happy with the current situation with the PS3," said Newell. "We're solving it now in a way that is going to work for our customers, rather than assuming something is going to emerge later that will allow us to fix this."
Valve also revealed that it had at one point been working on a game about fairies, before axing the project in favour of Left 4 Dead.