In Yubotu, the goal is to locate a fleet of ships within a grid. There are three difficulty levels to choose from and four fleet sizes - the standard 10 ship fleet and three additional sizes (15, 20 & 25), unique to this version.
If you are stuck, check out the handy hint option, or the game can solve one cell for you with an explanation. All puzzles are solvable by logic alone.
Yubotu is also known as Battleship Solitaire. This version is adapted from the popular online program that has been generating well-crafted puzzles since 2007.