So let's put things into perspective. You're at the local video store looking for a video game to rent for the weekend. You see some really cool looking games (at least, to you they looked cool), but you can't play them; either because they're on a different console, or they're rated M and there's no way your parents would let you take the game home. You sigh, and return to the section pertaining to your console of choice.
Has this ever happened to you? What games did you want to play but couldn't due to certain circumstances?
Personally, I remember one of my greatest dissapointments was not being able to rent Dark Cloud or Okage: Shadow King because I didn't own a PS2 at the time. Something about the boxart for each game promised a unique experience that I could never fufill.
EDIT: I also remember wanting to play Maximo, and fondly remember watching my cousins play Tomba. Before it was ported, I also remember wanting Sonic Adventure 2. (Ok, I think that's everything).