This is a variant on the slitherlink puzzle invented by Nikoli (Japanese site). The trick here is that all the numbers are outside the loop; none are inside. As with all good puzzles of this type, there is only one valid solution — at least I think so, this is my first time creating a slitherlink puzzle at all. I’m very curious to see how hard or easy this is. I created it by “solving” it as I added numbers to a blank board, so I assume there aren’t too many challenging elements (other than perhaps where to start) but we’ll see.
This isn’t the traditional presentation for a slitherlink puzzle. Normally there are dots at the intersections and no lines, but I created this in a spreadsheet, so just know that the lines in the diagram below are just placeholders. You’ll need to decide where to put the actual loop. The goal is to fill in the lines to create a single closed loop that does not cross itself. Each of the numbers indicates the number of filled-in sides of the square around them. So a 3 has three sides filled in, a 2 has two sides filled in, a 1 has just one side filled in. So far that’s a standard slitherlink, but as I said above, in this puzzle the final loop will contain none of the numbers. Note that the outside edge counts — you can draw them as well. So the only possible solution for this small puzzle:
Good luck, and let me know how hard it is!