Platformer Game
Use physics and gravity
Pick a sprite or paint your own.
Pick a sprite or paint your own.
/pngs/choose_paint_tool.png
Shrink it
/gifs/shrink-sprite.gif
We can use variables to control how fast we move in the x and y directions and how strong the force of gravity is in the game.
Go to a location
Using 'My Blocks' can help make the code easier to understand and to reuse. Make a block and name it spawn. 
Go to a location
Often games start in the lower left corner of the stage, but you can start anywhere you like. Your x and y coordinates might not match these.
when flag clicked
spawn
define spawn
go to x (-200) y (-140)
Don't flip upside down
Many sprites flip upside down when facing the left. This fixes that.
set rotation style [left-right v]
Make variables for x and y velocity
x velocity is how fast you are moving in the horizontal direction (left or right). y velocity is fast you are moving in the vertical direction (up or down).
Set velocity variables to 0
set [x-velocity v] to (0)
set [y-velocity v] to (0)
Make gravity
Gravity is a force affecting our y velocity. Make another variable for gravity. Do you think gravity will be a force in the positive y direction (up) or the negative y direction (down)? Read more about gravity on the NASA website.
Set gravity variable
On earth, gravity is a force of approximately 10 meters per second squared. Later, you can experiment with what it would be like if gravity changes in your game.
set [gravity v] to (-1)
Type this backwards to unlock:
Full code example
when flag clicked
spawn
define spawn
go to x (-200) y (-140)
set rotation style [left-right v]
set [x-velocity v] to (0)
set [y-velocity v] to (0)
set [gravity v] to (-1)
Use the keyboard to move left and right
Main Game Loop
This project uses a main game loop. Inside this forever block, Scratch will keep checking if the character is moving, jumping, or falling.
Start with these blocks
when flag clicked
spawn
forever // add this block
x velocity
First, we set the x velocity based on which key is pressed. Then we will update the x position of the sprite based on the x velocity.
Running?
Make a block called running? and add it to the game loop
when flag clicked
spawn
forever
running? // add this block
To the right
define running?
if < key [right arrow v] pressed? > then
change [x-velocity v] by (1)
end
To the left
How could you make the player move left?
To the left
What do you need to change to make the player go left?
Slide to a stop
The player should gradually slow down when you stop pressing a key.
set [x-velocity v] to ( (x-velocity) * (0.9) )
Move the player
Finally we can move the player using the x velocity.
change x by (x-velocity)
Type this backwards to unlock:
Full code example
define running?
if < key [right arrow v] pressed? > then
change [x-velocity v] by (1)
end
if < key [left arrow v] pressed? > then
change [x-velocity v] by (-1)
end
set [x-velocity v] to ( (x-velocity) * (0.9) )
change x by (x-velocity)
when flag clicked
spawn
forever
running?
You will need some platforms to stand on.
Paint a backdrop
/gifs/paint-a-backdrop.gif
Draw the ground
/platformer/paint-the-ground.gif
Make a falling? block
Create a 'My Block' called falling?
Add it to the game loop
when flag clicked
spawn
forever
running?
falling? // add this block
Gravity always affects you
define falling?
change [y-velocity v] by (gravity)
change y by (y-velocity)
But go back up if you hit a platform
if < touching color (#000000) > then
change y by ( (0) - (y-velocity) )
set [y-velocity v] to (0)
Type this backwards to unlock:
Full code example
define falling?
change [y-velocity v] by (gravity)
change y by (y-velocity)
if < touching color (#000000) > then
change y by ( (0) - (y-velocity) )
set [y-velocity v] to (0)
when flag clicked
spawn
forever
running?
falling?
You can't walk through walls...
Add an obstacle to the platform backdrop
/platformer/wall.jpg
Make a 'My Block'
Make a 'My Block' called wall? and add it to the game loop.
Make a 'My Block'
when flag clicked
spawn
forever
running?
falling?
wall? // add this block
Don't walk through walls
define wall?
if < touching color (#000000) > then
change x by ((0) - (x-velocity)
set [x-velocity v] to (0)
Type this backwards to unlock:
Full code example
when flag clicked
spawn
forever
running?
falling?
wall?
define wall?
if < touching color (#000000) > then
change x by ((0) - (x-velocity)
set [x-velocity v] to (0)
Jump over obstacles and to reach platforms
Make a jump? block and add it to the falling? definition
define falling?
change [y-velocity v] by (gravity)
change y by (y-velocity)
if < touching color (#000000) > then
change y by ( (0) - (y-velocity) )
set [y-velocity v] to (0)
jump? // add this block
Which key will you use to jump?
define jump?
if < key [up arrow v] pressed? > then
Jumping force is the opposite of gravity
Experiment with different jumping abilities by changing this number.
change [y-velocity v] by (12)
Type this backwards to unlock:
Full code example
define falling?
change [y-velocity v] by (gravity)
change y by (y-velocity)
if < touching color (#000000) > then
change y by ( (0) - (y-velocity) )
set [y-velocity v] to (0)
jump? // add this block
define jump?
if < key [up arrow v] pressed? > then
change [y-velocity v] by (12)
Add this code if you want to be able to walk up ramps.
Make a block call ramp? and add it to the game loop
when flag clicked
spawn
forever
running?
falling?
ramp? // add this block
wall?
Move up a bit, if you're stilling touching the wall color, then you're not on a ramp so move back down.
define ramp?
if < touching color (#000000) > then
change y by (2)
if < touching color (#000000) > then
change y by (-2)
Get to the goal!
Add a goal
Use the art tools to add a unique color to the backdrop for the goal. Alternately, add a new sprite to be the goal.
Impossible?
Play test your level and make sure you can get to the goal. Move things around and redraw platforms until it is not too easy or too hard.
Make a block called win? and add it to the game loop
when flag clicked
spawn
forever
running?
falling?
ramp?
wall?
win? // add this block
How do you know if you won?
define win?Use the eyedrop color picker to select the exact color of the goal. Or use this if you chose a sprite for the goal:
if < touching color () > then
touching [Giga v] ?
What happens when you win?
say [You won!] for (2) seconds
Type this backwards to unlock:
Full code example
define win?
if < touching color (#fffb19) > then
say [You won!] for (2) seconds
end
when flag clicked
spawn
forever
running?
falling?
ramp?
wall?
win? // add this block
What happens on the next level?
Paint a new level
Create a new backdrop. It's easiest if the spawn point is in the same place. 
Spawn when you get to the goal
define win?
if < touching color (#fffb19) > then
say [You won!] for (2) seconds
spawn // add this block
end
Switch backdrops when you win
define win?
if < touching color (#fffb19) > then
say [You won!] for (2) seconds
next backdrop // add this block
spawn
Switch to first level when you start
when flag clicked
switch backdrop to [backdrop1 v] // add this block
spawn
forever
running?
falling?
ramp?
wall?
win?
Watch out for the baddies!
Add an enemy sprite
Put the baddy in the location where it should start and change the size.
Only show on the right level
when backdrop switches to [backdrop1 v]
hide
when backdrop switches to [backdrop2 v]
show
Glide back and forth to guard the goal
Scratch will automatically update the x and y coordinates for the position of your sprite. Your numbers will be different than this!
when backdrop switches to [backdrop2 v]
show
forever // add this block
glide (3) secs to x (200) y(-130)
Guarding
Drag the baddy to the next location it will move to.
Glide to the the next position
when backdrop switches to [backdrop2 v]
show
forever
glide (3) secs to x (200) y(-130)
glide (3) secs to x (35) y (-130) // add this block
Type this backwards to unlock:
Full baddy code example
when backdrop switches to [backdrop1 v]
hide
when backdrop switches to [backdrop2 v]
show
forever
glide (3) secs to x (200) y(-130)
glide (3) secs to x (35) y (-130)
Make a baddy block
Switch to your main character sprite.
define baddy?
when flag clicked
switch backdrop to [backdrop1 v]
spawn
forever
running?
falling?
ramp?
wall?
win?
baddy? // add this block
How can you tell if you run into the baddy?
if < > then
Touching?
touching [Frank v] ?
Restart!
if < touching [Frank v] ? > then
spawn
Type this backwards to unlock:
Full character code example
define baddy?
if < touching [Frank v] ? > then
spawn
when flag clicked
switch backdrop to [backdrop1 v]
spawn
forever
running?
falling?
ramp?
wall?
win?
baddy?
What else can you add?
Hide variables
/platformer/hide-variables.gif
Add lava
Add patches of lava to your level. You might use this block:
if < touching color [#ff0000] > then
Spinning obstacles
when backdrop switches to [backdrop1 v]
hide
when backdrop switches to [backdrop2 v]
show
forever
turn right (1) degrees
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