If you bought Superhot, you're going to get the new sequel for free. Doesn't include giveaways or bundles though.
I can't figure out where I got my copy. I feel like it was a bundle, but ITAD doesn't list any bundles I bought.
I added it to Steam at the end of 2016. I guess it doesn't matter where I got it; very little chance I'll get the sequel free I guess.