RimWorld will be getting some upgrades to make it look great on the Steam Deck but it's going to take a little longer.
In a statement released on Steam, Ludeon Studios head wrote that the developer who was working on it lives in Ukraine, and the situation there right now of course is terrifying. They mentioned getting a Deck to this developer was delayed and the current situation means progress couldn't be made on it. Another developer is now taking over the Steam Deck upgrades instead but it's going to take a little bit longer.
Currently, they said it does work on the Steam Deck (and it has a native Linux version) but "there are a number of UI issues and some general jankiness we intend to solve with an update".
For now RimWorld is officially listed as "Playable" for Steam Deck, with the notes mentioning it sometimes shows the wrong icons and some text requires manually opening the keyboard. Ludeon Studios suggest waiting for their update to be out before diving in.