Glaugust: Exploring in the Age of Creation
Before you start playing your preferred dungeon/wilderness game prepare at least a d4 of dungeons. They should vary in size, difficulty, and purpose. Once you have enough dungeons to populate at least a d4 add "A Dungeon Appears" to your encounter table. When this is rolled, roll on your new dungeon table and place the rolled dungeon. Injecting a new dungeon into a random location will bring about violent and interesting changes! Embrace chaos, losing is fun, and if you think it's too weird, go weirder.
Note: You could easily adapt this to any physical feature. Places change, new towns pop up, reasons and answers for why will come about naturally in the push and pull of play.