I know this sounds really odd, but this makes sense with the program I intend to be reading my map’s data.
I would like to be able to give a cell a numeric value. Ideally, just be able to straight-up paint numeric values into my cells.
Either as a special kind of layer that takes numeric values, or as an unspecified attribute for the cell on a layer.
I imagine this could be very useful for all kinds of maps/games. For example, if someone wants to set encounter rates in an RPG. Personally I want to use this for setting Z/height values and also for brightness values, but there are a lot of ways it could be useful to just assign numbers that the game can read.
I was about to create a large collection of tiles that just have the numbers written on them, but it would be so much easier if I could just directly assign a numeric value in the editor.
There is no such feature in Tiled. It’s been requested, but since tiles are already just numbers, it seems like a lot of work for what is arguably more flexibly and conveniently done with a tileset. If this were a feature, people would almost certainly ask for visualisation (e.g. visualising heightmaps as grey values or colour-coding specific values), at which point it just becomes effectively a Tile Layer again xP
You might be able to find an existing number tileset if you don’t need too many different numbers. You can also use Tiled scripting to generate such tilesets (my Tileset Heatmap script does this to display the heatmap), but generally it’ll be better to create normal tilesets using an image editor.
In case you don’t need numbers displayed on the tiles and just need colour coding (e.g. a greyscale gradient for brightness/height): most image editors make it easy to generate a gradient with a given number of values - make an Nx1 image, and fill it with your gradient (the larger N is, the more diverse the colours in the gradient will need to be). In Tiled, make a tileset of this image with 1x1 tiles and set the tile render size to grid and the fill mode to stretch so the tiles fill their cell when displayed by Tiled. Such a tileset should be small enough that even if your Tiled map loader doesn’t let you skip loading the image, it won’t take up a lot of space/memory. If you need a few visually distinct values, you can make a similar Nx1 tileset with manually coloured pixels.