creating mesh from grid during game? (Q?)

I have a grid as a background… I want to draw a 2d object (square, triangle, or other shape) and have the game create a mesh the shape and size of the 2d object while running in the game engine. This will be during the creation stage, so it doesn’t have to run fast, but is it possible? Do I need to use python, can I use logic bricks? Thanks in advance.

It is currently not possible to create new vertices or faces in-game. You can duplicate an existing mesh with LibNew and modify it.