The hardest level I have ever played was the hoverbike level in Battletoads. Whoever thought of putting random barricades in a 400 mile per hour speeder bike section with .02 seconds of warning needs to be shot.
A close second would be beating all the Staff Ghosts in F-Zero GX without a custom car. That had me punching the wall at a few points.
A close second would be beating all the Staff Ghosts in F-Zero GX without a custom car. That had me punching the wall at a few points.