R.E.P.O.

R.E.P.O. is an online co-op horror game from semiwork, released in early access. You and up to five friends venture into terrifying locations to extract valuable items, and your employer is a mysterious computer intelligence.

Everything here is built on physics: valuables — from heavy pianos to fragile ceramics — have to be carried out without breaking. You get a physics-based grabbing tool, and you need teamwork to get the cargo to the extraction point intact. Even the monsters obey the law of gravity. Proximity voice chat is on, so shouting is unwise when something is listening nearby. With the money you earn you buy upgrades and weapons from your “generous” creator.

According to HowLongToBeat, the main run takes about 9 hours and the full set about 37, but the sample is still small and the game is still developing. A month is plenty. It is an online co-op game that needs the internet; Steam also lists it as single-player, so you can play alone too.