Create a variable named `y velocity`
Create a variable named `ground level`
Set `ground level` to the Y position where the sprite should stand
Set `y velocity` to `0` when the game starts
Use a `forever` loop
Add a small negative change to `y velocity` each frame to simulate gravity
Change the sprite’s `y` position by `y velocity`
If the sprite touches the ground level, set its `y` position to `ground level`
If the sprite touches the ground level, set `y velocity` to `0`
If the sprite can jump, set `y velocity` to a positive value when the jump key is pressed
If needed, use separate variables for `x velocity` and `y velocity`
If needed, add collision checks for platforms and walls