We're putting the demo live a few days in advance of PAX Online, to give folks more time to notice it's there, try it, have fun, etc! We've gotten a lot of "wait the demo was live? and now it's gone again? AAAAAAA" feedback previously, so hopefully this helps.
Demo's over here: https://store.steampowered.com/app/971030/SkateBIRD/
It'll still get pulled down at the end of PAX Online (it ends July 18th), so you've got until around then, but this gives you a few more days. Also. I should probably mention that I didn't integrate the Steam store stuff yet, which means if you copy the game somewhere and just run the exe, it would probably work forever, since I didn't add kill code or anything? Weird. What a weird factoid. Anyways have fun!