What's up in the world of Area 51 puzzles? The amazing Otto Janko has created a Java applet for Area 51 puzzles. In the coming weeks, I plan to convert some of the puzzles in the archive to a usable format for the applet and post them here on the site.
Area 51 puzzles are fence-building style of puzzles based on several clue styles found in other fence-building puzzles.
Area 51 puzzles may contain slitherlink-style clues. These clues consist of a number in a cell that ondicates the number of fence pieces around that cell.
Area 51 puzzles may contain corral-style clues. These clues are numbers surrounded by a circle that indicate the number of cells inside the fence that can be traveled to in the straight line up, down, left, and right from the clued cell. (Plus the clued cell itself.) As such, the clued cell must also be contained inside the fence.
Area 51 puzzles may contain cacti, which clue cells that must be outside the fence when the puzzle is complete. In some fence-building variations, these have been clued by trees or wolves (e.g. Wolves and Sheep variants).
Area 51 puzzles may contain masyu-style clues. These clues are filled and unfilled circles found on a grid intersection, as in masyu.
Filled circles must have the fence pass through them with a 90 degree turn on the clued intersection itself, and with straight fence passing through the previous and next intersections along the fence.
Unfilled circles must have the fence pass through them with a straight line on the clued intersection itself, and have a 90 degree turn on one or both of the previous and next intersections along the fence.