Voidtrain (opens in new tab) is the kind of game that grabs my interest based solely on the underlying concept. You're part of the crew of an old train—a simple trolley, really, although you'll improve and expand it as you play—but the rails you ride are interdimensional, running through Stargate-like portals into a weird world filled with all sorts of strange, dangerous creatures. And a lot of them don't seem to happy to see you.
It's a survival game, according to the Steam listing, that drops a group of mechanics on an old train into a unique world governed by very different physical rules. Much of the journey is governed by the way the train is upgraded: You can extend it with extra cars, upgrade the engine to steam, diesel, or Tesla, or improve its defensive capabilities.
The further it's upgraded, the faster it goes, and the more challenging the ride becomes. Because of that, each trip promises to be unique: "Each time there's a new path to go on, new lands to discover, and a new train to build."
Voidtrain will support singleplayer journeys, and online co-op play for up to four people. It's expected to be out in in the fall.