The Floor is Lava also known as Rising Lava Challenge.
Notice: If the lava stops somehow, just go in this corner and break the stone up there. Be careful to not break the observer or the command blocks.
https://ibb.co/Hr3JKgH

It's just a world with a border of 128x blocks but lava rises every minute. You get no advise if the lava rises up so it will be more exciting and so the things are more interesting the map is on hardcore mode. There is an end and nether many hidden chests over there and a lot of spawners. Trust me a lot. Lexus_pro's fault.
Also if you beat the ender dragon in this gamemode, you should consider yourself a good player. If you fail you are just a potato. The challenge is so easy that makes me cry.

Before playing read the stuff near you. There is a tutorial book in the chest. Learn how to make the Glitch Box and many more.

Challenges:

Let's spicy the things up!
1. Make a Water Bucket.
2. Mine an Obsidian.
3. Go to Nether
4. Find a Diamond.
5. Make a Glitch Box.
6. Bring any mob from nether to lava world.
7. Go to END
8. Beat the ender dragon.
9. Feed to cows in order to make a baby.
10. Grow a tree.
11. Find Redstone in 5 minutes.
12. Punch your mate in lava [Multiplayer only]
13. Remove all lava in the world. [Don't do it]
I hope you can at least survive ROLF!