Grid with snapping objects

So, I got a gameobject called "Grid" and I made a spawner which spawns the "Grid" in a grid pattern, im trying to achieve a instantiated object (which follows the mouse) to snap to one of the grids and spawn.

I cant seem to figure out how to instantiate the objects right and how to make them react to the gridsystem. Any help is appreciated.

 

You can use a raycast to determine where the mouse is pointing. Take the position of the raycast's hit and adjust it properly.
For the following example i assume your objects always occupy one cell and the cells are 1x1 units, the pivot of your objects are always centered, i.e. (0.5, 0, 0.5).

Raycast hits P1(2.33, 0, 5.83) and thus you need to place the object at P1'(2.5, 0, 5.5).
One way to find the final position is float to integer conversion, which results in (2, 0, 5). Place your object at this position with the desired offset (0.5 in this example).

This is a basic approach and will surely need some adjustments to fit your needs.

 

Thank you for clearing this up for me, I will give it a shot.