My idea is as follows: the player gets a 32×32 grid with trees, rocks and sand. The player then has to advance through the ages with increasingly good technology. The art style will be isometric, although I don’t know if it can be considered true isometric. The graphics will be  easily exchangeable by replacing the sprites bundled with the game.

Oh, and the starting world will be randomly generated with a properties file where one can change the stats for their world.