Relativistic Asteroids is just Asteroids -- but with (some) relativistic effects added -- specifically, length contraction and time dilation.
As your ship accelerates, the little triangle that represents it visibly shortens (length contraction), and if you rotate, contraction is retained in the direction of motion, but not the others.
Time dilation isn't particularly notable--except that your bullets travel a shorter distance (when fired in the direction of motion), presumably because, in their frame they "expire" more quickly relative to the reference frame.
