I'm thinking of one in Dance Dance Revolution, of all places. Specifically, the extra stages in DDRMAX and MAX2. For the uninitiated, whenever you unlock an extra stage, your only choice of song is one insanely fast track and insanely hard chart. I can pass just about any level-9 (out of 10, at least on the old pre-X scale) chart without needing to "jump" on a DualShock controller and give my feet a rest, but the level-10 charts which are reserved for these boss songs are just beyond my physical ability. At least the later games let you choose a song for their extra stages.