Enemies
Gemstone Hunter is pretty easy right now. You are free to run around collecting all of the gems you want at your own pace with no chance of ever triggering the dreaded "die" animation. Not for much longer, though—time to add some zombies to the mix!
As with the Player and Gemstone classes, the Enemy class will be derived from the GameObject class, allowing it to exist within the world and, like the Player class, detect collisions with the tile map.