How can I find all of the instances within a set area?

I apologise if this is formatted badly, it is my first post here. I am trying to use a system, where a layout is covered in tiles. every 16 seconds, every tile, should get a seeded and weighted random value set to its state, determining its colour. I am in the process of establishing rules to set the weights of each outcome. I cannot seem to figure out a way to select all instances of "tile" within a certain radius of the currently selected one. Can anyone help me?

If the tiles are sprites you can simply use another invisible sprite with a circular collision polygon. And pick all tiles overlapping that sprite.

Or you can pick by evaluating distance to tiles:

System Pick Tile by evaluate distance(startX, startY, Tile.x, Tile.y)<radius