i will never forget the disappointment of collecting all the custom gems in sonic 06 because there was an achievement called "Super Sonic" whose hint was "obtain the all moves..." and Super Sonic was all over the early trailers for that game blowing up Eggman robots in the woods... but after the achievement popped i still got nothing... this is why i have trust issues :(
they should have at least revealed a cool secret like what color sonic's feet are