Yup. That's right. I'm released four survival maps... at once. Taking on the four toughest climates the world of Minecraft has to offer- desert, forest, tundra, and small ocean island- it will NOT be easy to survive each map. With a map pack like this it's hard to have a storyline, so we'll say you were in a teleportation experiment and went to the wrong place :P
But seriously, if you really want a story, be creative and think of one yourself. Anyway, to the details-

First- the maps from easiest to hardest-
-Sahara (plenty of grass, some tall grass, shouldn't be too hard to make a shelter the first night)
-Antarctic (you have six dirt blocks given to you and one tree, along with TONS of underground caverns)
-Amazon (mobs will spawn deep in the forest no matter what time, so this map is tough at all times of the day)
-Pacific (you are given ONE tree and ONE dirt block. Until you can stumble upon some underground dirt, this level will be a nightmare; on the bright side, there are some secret chests with diamond tools and armor in the caves below)

Now, the rules-
-There is a 256 block void at the edge of each map. Don't go over it, it's the edge of the challenge.
-You are allowed to break and place blocks, except for the signs and torches at the spawns.
-No using any mods that give an advantage to playing the maps (flying, x-ray, TMI, etc.)
-You must play on at least normal for the Amazon and Pacific, hard for the Sahara and Antarctic
-You MAY play this on SMP, but with no more than four people
-On the Pacific map, you are NOT allowed to leave the island to get anything (except dropped saplings)
-You may travel as far as you want underground on any map, just beeee careful
-No obvious cheating of any kind that I forgot to mention here

Now, the challenges-

~All maps
DO NOT DIE, IF YOU DIE YOU MUST RESTART
Do not let a creeper explode... ever. If you fail this you just don't win, but you may continue.
Collect both a gold and green music disc. Be creative as to how.
~Sahara
-Build a house out of cobblestone with at least 8 windows
-Get 16 glowstone blocks from the nether
-Make an entire suit of iron armor
-Make a diamond pickaxe
-Make an automatic cactus farm and collect at least 100 cactus
~Antarctic
-Make 4 bowls of mushroom soup
-Make a plank house
-Travel to the nether
-Make an entire set of iron tools
-Make a fancy looking lava fountain
~Amazon
-Make a wheat farm with at least 25 wheat growing at once
-Kill at least 5 spiders
-Catch at least 10 fish
-Kill 10 skeletons with a bow and arrows
-Make a boat, explore the river long enough to know its path (if you can make a map, that will satisfy this challenge)
~Pacific
-Make a cobblestone house with at least 10 windows
-Catch at least 10 fish
-Make a tree farm with at least 6 trees
-Make a block of TNT, detonate it (wherever, undeground works)

Additional Notes

If you want to make any of these maps in a video, please give credit to s15c at the start and end of each video, and link this post on Planet Minecraft in the description.