There does not seem to be much documentation on these experimental preview features, so please let me know if anything on this list is already included. I have experience with only one other tilemap program, Tiled, which I use with Tiled2Unity to create mesh-based tilemaps. Some of these features are included there.
- Arbitrary placement of tiles
You should be able to place any tiles arbitrarily, like any Unity object. This can be very helpful for tiles like loose grass, for example. Instead of having to create two sets of sidewalks - one with grass in between the cracks and one without - the grass can be placed as a separate layer on top of the sidewalk, in any combination. While you can make arbitrarily-placed objects children of a tilemap and become part of larger a large tilemap collider, as far as I can see, there is no way to make these objects actually be part of the tilemap like tiles are part of the tilemap. I would not want a thousand pieces of grass become their own hierarchy objects, even if children of the tilemap.
- Separate, customizeable grid to aid with arbitrary placement of tiles
When working in Photoshop, I have a grid with subdivisions that allows me to paint tiles in a consistent style. Similar subdivisions in Unity can help with the placement of arbitrary tiles and even other Unity objects. Beyond subdivisions, however, the grid should be customizable in terms of general size, color, etc. - anything that can help the user in making a map.
- Pixel-perfect placement of Unity objects, including arbitrarily-placed tiles
I currently use U2DEX mostly because of its customizable grid and ability to snap to the nearest pixel when placing Unity objects. Most tilemaps I’ve seen use pixel art, which means that most Unity games employing tilemaps will have pixel art Unity objects as well. Without U2DEX, my 1-pixel-to-unit sprites are placed at non-integer positions like 47.8, etc., and I constantly have to correct it. Perhaps I’m missing something important here, but this seems like a feature that’s been long overlooked.
- Pixel-perfect colliders
Like above, but with colliders. Edge Colliders are often not pixel perfect, as are Polygon Colliders, etc. If you ever tried editing a Polygon Collider 2D for a sprite object, you will see that it is always too “fine” for pixel art. There is no way to replicate the same Polygon Collider 2D exactly in two different objects via the collider “Edit Mode.” In Tiled, I can use the collision editor to make a polygonal collision object with lines that follow the pixel lines of my sprite perfectly, and Tiled2Unity can make that into a pixel-perfect Polygon Collider 2D.
Every collider’s “Edit Mode” should have the ability to edit it per-pixel/integer. For Box Colliders now, it has to be done manually by inputting whole numbers in its size. This is impossible for Edge Colliders or Polygon Colliders, however, and is still a drag with Box Colliders.
I include this as part of the Tilemap suggestion because most tilemaps are composed of pixel art, and thus most Unity objects will also be pixel art.
EDIT: I now noticed that polygon and edge colliders have the option of changing their vertices via input of hard numbers (must have been introduced a few Unity versions ago, as the option used to be greyed out for me, or maybe I did something to make the option accessible). This does most of what is necessary for pixel perfect colliders.
- Randomized tiles with weights
Tiled lets you select a group of tiles, and when toggling “random,” it will select one random tile as a brush instead of all of the selected tiles at once. This is good for painting variations of a tile quickly. A per-tile weight attribute can help with the random function choosing a certain tile more or less often. In Tiled, the default is 1; changing it to 10, for example, will make it 10 times more likely to be chosen.
- Cell size per layer
This can currently be worked around via a separate tilemap object with a different cell size, but I’m not sure what the best practices are regarding having multiple tilemap objects in a scene. Essentially, sometimes you have tiles that are different sizes. Personally, I work with 32 x 32 and 16 x 16 tiles, and possibly even more sizes in the future, within the same project. Tiled allows you to input a horizontal and vertical offset per layer, so it is almost as good as having your own different grid size layer.
