How about asteroid belt Parkour, jumping between asteroids in a huge black room decorated with planets, stars, etc. The only way to exit is through a spaceship you have to find. Maybe you could build it in the End or the Nether, and then you could portal back to the Overworld. Diamonds can be collected along the way, and you put them in an Ender chest so if you die you don't lose all your progress. If you get all the diamonds, you can throw them onto a weighted pressure plate or something, so that you can't cheat the system, and then the next level gets unlocked! Maybe the next level will allow mobs to spawn and stuff.

plus im making my own survival island map

Yes It will Be Cool

U want a skyblock parkour made of cobble and grass every 50 blocks?

What About Skyblock Parkour Cobble And Grass parkour andevery 50 block an skyblock island it will be cool but can give me a little credit 4 thinking of it