Minecraft Mob Mayhem

Minecraft Mob Mayhem!!!

What is it?
This is a game I made in a few days that resembles zombie mode in Call of Duty. When I was building it I didn't realize that :P The basis of the game is to survive through at the very least two rounds. When you start the game four different mob types will start spawning for one minute. After all the mobs stop spawning you get a five minute break to finish killing them all. After that five minutes has passed another round of one minute comes. Once that round is over you get the choice to either continue to the next round or quit the game.

Why should I download it?
Unlike most things I've built I actually enjoy playing on this one, It's like CoD: Zombie Mode if you like that kind of stuff, and the map is expertly crafted if I do say so myself. :P

Is it multiplayer?
Yes! I've made it so 1 - 3 people can play but you can easily add more items for more players.

Can I modify it myself?
If you want to modify it yourself go ahead. If you upload it somewhere I would like you to mention me though.

Additional Notes

There are some minecart tracks that are no longer in use. Please ignore them as they do nothing anymore.