Yes unfortunately and yet only for now. We just started with Mac (coin toss) and now we'll do our best to cover all of them soon.
That's sad -- from your demo video, I thought you were supporting Windows too (the minesweeper window). You might want to make that more explicit.
Hey both, we were overwhelmed by the interest (and therefore also wrt. requests for Windows & Linux support) but we've just set up this form to help us prioritize the next platform CoScreen should run on:
https://shorturl.at/koJX3
Point taken, we only have a raw windows prototype so far.