WorldBox – God Simulator: Ninja Turtle Achievement Guide

First click the Create a new world

Then create an Empty world and make it tiny
Create small island with 3×4 tile sized plain soil middle and mountain barrier around it

After doing these steps, pause the game and place these mobs inside the island in this pattern

1. Turtle
2. Nine(9) Fairies
3. Skeleton
4. Snowman

Give all creatures these buffs

1. Shield
2. Powerup
3. Coffee

Shield is for stopping them from killing each other, Powerup is for making them stronger & easier to see and Coffee is for making the turtle reaching the skeleton & attack faster
Make the time go 5x faster, press play and shower them with shield buff or skeleton will kill them all

Now simply keep buffing them with those buffs (especially with shield) until you get the Ninja Turtle achievement. This should only take about 5 minutes.
You can check your turtle’s level by trying to click it in creature cluster
Sometimes rng might make you fail, but simply kill all creatures and place new ones and try again.