A new beta release for the Steam client includes scoped-achievements.
Achievements can now be split into game mode specific, DLC specific and seasonal specific achievements.
In theory, this will now allow players to achieve achievement completion, even though they're not interested in the multiplayer aspect of a game.
In Cities Skylines for example, in the game itself you decide when you've won enough, there's not a specific point when the game tells you you've won and you can stop playing now, so many players consider getting all achievements as completing the game. But some of the achievements are only possible to complete with certain DLC. An achievement "Make a Hot-Air Balloon Line" can only be done if you have the DLC letting you create Hot-Air Balloon lines, and so if you can't do 30% of the achievements because of DLC you don't have, the maximum completion you can attain without paying is 70%. In the prior format at times it might not be clear which achievements required DLC, including hidden ones. New scoped format is an improvement.