I have 2d grid in a 3d world facing the world up. My camera is setup so it shows an isometric view of the grid.
I want to get the player's input in screen space (cyan) and find the same point on the grid (purple) ignoring the z position which will ultimately select the nearest tile (red square) from the input. I want to do this without using colliders as there could be hundreds of tiles in the same scene.
I want to know how I can project the screen space point into the 2d grid in a 3d world. The image below summarizes what I want to achieve.