To play the O-Sim 23 you simply need to add the free DCL O-Sim 23 to your library.
O-Sim 23 is out now!
Source: Steam Community (opens in a new tab)
Build and release context
Steam update times within 24 hours of this post. Matching dates do not confirm which build it describes.
Build 10243021 · public branch
Steam updated · First observed