A hexagon grid with different possible attributes for each hex is shown, as well as a bunch of logic rules.
Using those rules, you have to whittle down the possibilities until every hex has both a single object in it as well as a path that goes through it from one edge of the hex to the other, and the path makes a single coninuous path through all the hexes.
The presentation looks super old and retro, but it's a lot of fun and I keep coming back to it. It's available for Windows, Mac, and mobile.
There's also a bunch of other logic puzzle games on the site as well, and they're all interesting, but this one is my favorite.
Although I'll give an honorable mention to Willa's Walk, too, a game where you deduce a loop through all the rooms by using a few simple rules to deduce which doors the path will go through and which are actually walls.
Still trying to crack Star Battle/Hoshi. I invented some advanced techniques but there are some puzzles that stump me. There must be more tricks to learn, instead of brute force and backtracking.
Curse of the Golden Idol