While it's not a 3D polygon shaded game or anything of that ilk, The Settlers on the Amiga is a perfect example of what a well written and highly optimised machine specific piece of code can do...
Even on a basic 020 A1200 when you consider the amount of calculations going on, both onscreen and offscreen (up to 65535 characters/people per player) then it really goes to show just what a well written piece of code can achieve even on a lowly 020...