Markus had recently left his job as a game developer and wanted to develop his own game. He decided to develop Minecraft using Agile. He main focus of Minecraft was to keep the game simple, accessible and fun.
Markus continues to play Minecraft alot. He's built hundreds of towers and flooded more caves than he cares to remember. He believes that if part of the game isn't fun, it shouldn't be there and he will remove it. His philosophy is that if he can combine enough fun, accesssibility and building block for his game, Minecraft will be a melting pot of emergent gameplay.
Persson believes that all good stories have a conflict, and that all good games tell a good story regardless of if it's pre-written or emergent. Free building mode is fine and dandy, but for many people it will ultimately become boring once you've got it figured out. It's like playing a first person shooter in god mode, or giving yourself infinite funds in a strategy game.. a lack of challenge kills the fun.
For survival mode, Persson believes the game should be too difficult than too easy. That also means I'm going to have to include some way of winning the game (or some other climax) to prevent it becoming too exhausting. But if it's no fun, he will redesign.
The future of Minecraft
For as long as people enjoy and purchase the game he will develop extensions after the game is done.
Once sales start dying and a minimum time has passed, I will release the game source code as some kind of open source. I'm not very happy with the draconian nature of (L)GPL, nor do I believe the other licenses have much merit other than to boost the egos of the original authors, so I might just possibly release it all as public domain.