Valve launched the first "Steam Dev Days" conference in January of last year which is the only industry only show around, but it seems that they won't be doing the same for 2015.
A discussion with a Valve representative at Gamasutra revealed that it might not be the last though, and that Valve are going to have a "larger than normal" presence at GDC (Games Developer Conference) in this coming March.
Steam Dev Days was a great way to brief a large number of Steam developers. This year our focus will be a bit different, so we are planning a larger than usual presence at GDC. So, there will not be a Steam Dev Days this year, but we will certainly consider doing it again in the future.
In 2014 their focus was on their new hardware products such as the Steam box and VR initiatives, which "made sense" for Valve to do that year.
The question is though, what is the "larger than normal" presence at GDC all about? I can bet that a lot of people will be saying that Half-Life 3 is finally being revealed, and that may be a possibility, but I highly doubt it.
What do you think they could have planned for GDC? Let us know!