As part of preparation for the v3 update, the launcher settings have been modified to use the new filenames. However, this means that the game may give an error when trying to quickly launch it from the Steam Library shortcuts. To open the game when trying to play v1 (original) or v2 (current), there is an alternate launch option that is available when launching the game from the main library page or the collections page. Make sure to select "(v1/v2)" as your launch option from the menu that appears. (If you use shortcuts, you may need to update your shortcuts.) Once v3 releases, both launch options will remain available, with the default option launching v3+ and the alternate option launching v1/v2.