Valve working on codename Citadal, is this Half-Life 3?!

Valve has changed in the last few months with management reportedly making staff publish content quicker, rather than no communication or months of no updates on internal projects... enter codename Citadel.

Citadel turned up in a low-level engine update to Dota 2 which is based on the Source 2 engine. Citadel is the latest to join the list of Source 2 projects with Dota 2, Half-Life VR, and Left 4 Dead 3. In the video above, Tyler McVicker from Valve News Network said that Citadel is the work of Valve pushing employees to ship content more often, and now we're seeing the effects of those internal changes.

What do you think Citadel will turn out to be?