I second-guessed my original idea and thought up a Zelda-like game, except in reverse... So instead of being an adventurous hero going through dungeons to get powerful items that will help with traversing the world, you're a retiring hero who just finished a big quest and wants to go back to a simple life, returning all the powerful items to the dungeons he/she/they stole them from, making the adventure harder in the process.
... Then I realised I should probably stick with my original plan, seeing as I only have a week and I'm working solo. Might make that game later though, who knows. But anyway, maybe that can spark some ideas!