This is similar to Slitherlink, and is arguably a variant. This puzzle appears in "Challenge Your Brain Math & Logic Puzzles" (Dave Tuller & Michael Rios, Puzzle Wright Press).
Puzzle and Goal
An unsolved puzzle consists of a hexagonal grid. Some numbers are placed in the grid.
The goal is to draw a single open path that satisfies the clues.
The solved grid must satisfy the following conditions:
The numbers indicate how many neighboring cells the path travels through.
The path does not travel through any cell with a clue.
The path does not turn 60° at any point.