I think Windmill should fall into the hopper category since it requires a hurdle to move.
Well, it doesn't hop over anything. So it's not a hopper. But because it does require a piece to go around, it is also different from a regular rider. Maybe it could be classified as an Orbital Rider, because it requires another piece to orbit around. The question that remains is whether this category belongs under Riders or under Hybrids. It has one element of hopping, which is requiring another piece to move, though it works differently than hopping does.
I suppose what it has in common with hoppers is that hoppers and orbital riders could both fall under a larger category of pieces that are dependent on the proximity of another piece to move. But without lots of other piece falling into this category, it may be best to keep Hoppers as a top-level category.
Well, it doesn't hop over anything. So it's not a hopper. But because it does require a piece to go around, it is also different from a regular rider. Maybe it could be classified as an Orbital Rider, because it requires another piece to orbit around. The question that remains is whether this category belongs under Riders or under Hybrids. It has one element of hopping, which is requiring another piece to move, though it works differently than hopping does.
I suppose what it has in common with hoppers is that hoppers and orbital riders could both fall under a larger category of pieces that are dependent on the proximity of another piece to move. But without lots of other piece falling into this category, it may be best to keep Hoppers as a top-level category.