A pretty solid rule of thumb is that 32 bits has enough precision for rendering, physics needs doubles if it's going to use a lot of iterations. Simplified mode

A pretty solid rule of thumb is that 32 bits has enough precision for rendering, physics needs doubles if it's going to use a lot of iterations. Simplified models like Super Mario jumps or the tractor beam in "Thrust" (single rigid joint) can get away with 16-bit fixed point precision. OTOH rendering of geometry only needs about as much precision as the display offers, which often means 8 bits on older hardware.