I also remember playing that Powder Toy game on my phone in grade school, and I have a ton of nostalgia for these kinds of physics.
Will there be significant hidden mechanics/riddles/lore built into the world in a Noita-like way, or is the physics engine the limit of that comparison?
How does such a deal work? Do they contact you? Or are there places where you can promote your game to get it on Game Pass?
It's my publisher (Hooded Horse) handling it so not sure about the exact process. I don't think it's easy to get a day 1 deal though so I'm very grateful for it.
Good luck on your game & launch!