So this is really short because we're already at the exhibition and there's people coming in ... but ... if you want to try the demo we have prepared for Gamescom 2016, there's a new branch gamescom-2016-demo.
This is "developer quality", in other words: It's good enough to demo but we have, for example, disabled all quality settings, skipping and a few other things. So if you don't have a 980 Ti +, this may not work too well for you.
Also, you cannot start the game from within the game. But there's a button on the companion Window that says: "Start Session", and then the action immediately begins. One thing you'll see here is our new intro-sequence, and it's much faster than the old one.
So, let us know what you think in the forums; eventually we'll probably make this an official demo but it's a big difference whether you create a build where you know exactly what to touch and what not to touch or whether you build something for everyone to play with.
You may get hangs at the end of the session (and possibly also at the beginning of the session) because it tries to write the highscore to a local file. What's behind this is a feature we'll also add to the main builds: "Party Mode", where you can play with a few friends and have a local highscore.
There's not much missing for that (we just need to give you a way to select the file yourself instead of having a network share hardcoded in the build ;-) ).
Anyways, we hope this works for everyone and you'll have fun ... even if you didn't make it to Gamescom this year :-)
EDIT: Ooops, I forgot to add a link to how you select branches in Steam: Opting In and Out of Steam Client and Product Betas