Self described as a Sudoku challenger, Hidato is a number puzzler that requires you to fill in the sequence of numbers across a partially filled board. Numbers must be connected either side-by-side or diagonally in sequence, and there is only one solution per board.
The gameplay seem simple but seems to fulfill a similar sort of immersive satisfaction as a game like PathPix. The developers are also offering a good sampling of 10 puzzles for free in a Lite verison that should give you a good taste of the game. The full version of the game contains 100 boards.