Grid rendering option only for places where can be built on?

People seem to love grids on the maps, not me! Sometimes they make it look good, but on some maps it just makes it look worse! There is a lot of different opinions when it looks good and when it doesnt.

So, i think the best solution is to simply add automatic grid rendering with transparent color on it - if the user wants. It could be toggled on/off by the user.

How it would work: it would draw the grid ONLY on the areas where player can build, so the walkpath will be distinct from other areas. This should be easy to implement, just render two textures: one without a grid, and one with it. Doesnt affect performance at all, so not a bit more real-time drawing of stuff on the screen.

This wouldnt be just purely esthetical purpose, but to also help the player to place/plan towers.