One of the best games of all time, in my opinion, is The Legend of Zelda: A Link to the Past. I have it for the GBA, and I love it. But once you've beaten the game, what else is there to do?
One way to keep yourself occupied with this game is by embarking on the 3 Heart Quest. In this quest, you go through the game with ONLY 3 HEARTS. Not only that, you have to defeat Ganon and the 4 Link Clones. It does involve glitching the game, but MOST of this is possible on the actual GBA (I myself have done it). Here's the playlist:
http://www.youtube.com/view_play_list?p=CE6CE03FD2BAE044
The walkthrough, consisting of 25 parts can be divided into 5 categories:
Parts 1-10: Getting the items needed to complete the 4 Sword Dungeon.
Parts 11-14: Defeating the first 4 bosses in the 4 Sword Dungeon (you can enter this dungeon without linking up by glitching).
Parts 15-20: Getting the items needed to defeat Ganon.
Parts 21-23: Completing the extremely tough Ganon's Tower.
Parts 24-25: Defeating Ganon and the 4 Link Clones.
So, yeah, for all those who own A Link to the Past, and want a new challenge to the game, try out the 3 Heart Quest.
Oh, and please rate and comment on the vids. Thanks!