Changes:

World:

• The world is now twice as big(256x256).
• Reduced world generation time.

Zombies:

• Zombies can now interact with "balls".
• Zombies now spawn at the right position when loading a world.
• Zombies no longer spawn in huge amounts.

Tiles:

• Most tiles now have shadows.
• Added "path" tile, increases player speed when walked on.
• You now walk even faster on "ice" tiles.

Other:

• Improved collision detection, you now fit more easily through doors.
• Added new main menu backgrounds, one is chosen randomly each time you enter the menu.