  "Eye-Witless", "Haisu" and "Oriental House" are genres of logic puzzles
invented by William Hu, and "Detour" is a genre of logic puzzle invented by
online user Guowen Zhang. Each of these puzzles revolves around constructing a
path or loop through the cells of a grid according to certain constraints given
by clues in the grid. We prove that deciding whether a particular puzzle in
each of these genres is solvable is NP-complete.
