It's a ***** to get a hold of legally...Working on it though. In the mean-time...Shawn MacDonald said:
Tetris. It's the only game l know of that is available on everything with a screen and anything resembling a keyboard (as of 2003 I think). It is the great-grand daddy of every current, casual puzzle game and proof that even the most simple of games can still hold up in this day and age.
Another would be the original Dragon Quest/Dragon Warrior. It isn't the best JRPG or all time nor am I saying it holds up. The ending is also really disappointing (I challenge anyone who calls ME3 WORST GAEM EVAR because of its ending to play through Dragon Warrior and tell me that one is better). The thing is though, it's like going to a museum. It's the great-great-grand daddy of JRPGs after all. It's also fairly short, taking about 15 - 20 hours depending on how grind-happy you chose to be.