Bigmap was a quick minimod project that never really got finished, intended to be a type of cross country road rally akin to Cannonball run, it's only use 
now is to show people how to make levels out of inidividual bsp models. Use impulse 47 to switch into "first person mode", the original manner to play. The overhead system was introduced later as I realized something like this would be great for a GTA clone...