>Explore environments from Half-Life: Alyx in your SteamVR Home space
>Alternate gun skins to embellish Alyx's arsenal
>Special Half-Life: Alyx-themed content for Counter-Strike: Global Offensive
>Community-built environments
>A set of Source 2 tools for building new environments will ship with the game, enabling any player to build and contribute new environments for the community to enjoy. Hammer, Valve’s level authoring tool, has been updated with all of the game’s virtual reality gameplay tools and components. 
I'm pretty sure that said something else shortly after announcement trailer. If it wasn't for the last sentence I'd just think it has some assets for building SteamVR Home bullshit nobody gives a fuck about. Even then, it's kind of convulted way to say SDK.