I'm happy to say that I'm at a point now where all of the base mechanics are in the game so I can start focussing on level design. Features I've implemented over the last few days include
- killing
- dying
- potions! (so you don't die)
- keys to unlock doors with
- doors to unlock keys with
- enemies not just straight up walking through walls
- Zombies and spiders to befriend (if by befriending you mean killing)

Good stuff.