I know this looks similar to skyblock but it is different. There are 3 spheres and 1 cube. Limited stuff. Play on Easy/Normal/Hard. You can play this online also.

Rules:
1.no flying or inventory editing
2.no killing yourself for hunger (unless it kills you)
3.don't go to main land until all challenges are complete

Challenges:
1. get to all 4 places
2. destroy the mob spawners
3. craft a golden apple
4. make a house out of anything
5. get to the nether
6. find all the treasure
7. make some giant mushrooms
8. have 12 diamonds
9. try not to die until all challenges are complete
10. make a 5 gold pickaxes
11. mine all the ores
12. retrieve the items from the sandstone sphere
13. find the ores
14. make green wool
15. make wool
16. make black wool
17. make 5 gold blocks
18. grow a birch tree
19. make a cobblestone generator
20. make a infinite water source

If you like the map give it a diamond!