http://store.steampowered.com/app/733070/Sudoku_Universe/
https://store.steampowered.com/app/858040/Sudoku_Jigsaw/
Sudoku Jigsaw - one hour
Source: Steam Community (opens in a new tab)
Build and release context
Recorded Steam release date:
Within one calendar day of this post (UTC). The listed date does not establish an exact launch time.