Unrailed! is an absolutely fantastic co-op game from Indoor Astronaut and Daedalic Entertainment that has you frantically build a train track to keep your train going as far as possible.
It entered Early Access back in September 2019, with Linux support arriving in February 2020 and now they're looking to the near-future with a full release approaching. They've not said exactly when but they have confirmed the price will be rising, so they've put it on a reasonably big discount (42%) until August 17.
This has to be one of the most hilarious and chaotic co-op experiences I've had in the last year. Trying to keep the momentum going, with one of you cutting trees while the other moves around resources and gets extra pieces of track put down all while you're trying to keep the train cool and not derail—with a partner it's just such good fun.
Additionally a demo and a new character will be coming soon, along with a promise of much more info to come.