Platform Game Mechanics

In this page I will show you how to add the following mechanics to your game:

1. Ladder climbing

2. Double Jump

3. Slippery Ice Block

4. Running

5. Wall Jump

6. Rope swing aka Grapple hook 

STEP 2 Player Climbing Sprite

When the player collides with the oLadder the state will change to "climb" state

While in the climb state the sprite will change to a sPlayerClimb sprite that we need to make lucky that the LPC sprite generator has a climbing sprite

It has 6 frames is 64 x 64 px and the vertical cell offset is 21

Like all your animated sprites make this have a middle center origin

.Creating the Climbing Pose

Game maker does not automatically use the LPC style sheet we have to convert it to different poses

1. Click on Add Sprite Icon click load sprite and then select Edit Sprite

2. Select Image Pull Down Menu and click Import Strip Image and load your character sprite

   1. 1. Number of images and number of rows is 9

      2. Image width should be 64

      3. Image height should be 64

      4. Vertical cell offset is 11

3. Click Convert

4. If your character has a colored background select Image Erase a color to make it transparent.

5. Save as sPlayerClimb

6. Select Middle Center for the sprite

STEP 3 Thinking About the Ladder

We will make these new mechanics as scripts so the step event code of oPlayer doesn't have to be changed (It will change a bit)

First we have to think about all the things we want to do with this climbing mechanic.

1. If we collide with ladder and press "W" key we want the sprite to change to the sPlayerClimb sprite and begin to climb up

2. We want the player to be able to walk through ladders staying in the walk or idle states this is why we will check if we or pressing the W key and colliding with oLadder

3.  If we move on ladder we want to animate sprite

4. We can climb between platforms

5. We can walk off ladders

6. We can move left and right on ladder

7. We cannot attack while on ladder

8. We cannot climb through platforms

STEP 4 Ladder Climbing Variables 

First lets add our climbing speed variable

Open your oStart object and add the new global variable under the other two global variables in the Create Event 

CREATE EVENT

//Variables this is your move speed and jumping distance

global.movespeed = 5;

global.jumpspeed = 20;

// New Global for Climbing Speed

global.climb_speed = 3;

STEP 5 Player Input and Climb State

Now we will modify our STEP Event code in your oPlayer object

In the Get Player Input area we are going to add two more keyboard checks so we can hold down the W key to climb Up or hold down the S key to climb down

STEP EVENT oPlayer

// Get player input

key_right = keyboard_check(ord("D"));

key_left = -keyboard_check(ord("A"));

key_jump = keyboard_check_pressed(ord("W"));

attack = mouse_check_button_pressed(mb_left);

wepselect = keyboard_check_pressed(ord("S"));

key_up = keyboard_check(ord("W"));

key_down = keyboard_check(ord("S"));

Now after we React to inputs we will check for the collision is the oLadder object

Place this code into the STEP EVENT of oPlayer inbetween the react to inputs and the Jumping and Gravity section

this will put us in a "climb" state if you are colliding with oLadder, turn off gravity and set our vertical and horizontal movement speeds

//Climbing Collision

if place_meeting(x,y,oLadder) 

{

state = "climb"

hsp=0;

vsp=0;

grav = 0;

vsp = global.climb_speed * (key_down - key_up);

hsp = move * global.movespeed * movefactor;

}

else

grav = 1;

Picture below shows where to place code

STEP 6 Switch Statement Code

Now we will add a new Case in the switch statement for "climb"

This code will make our character animate when moving or stop animating when not climbing on ladder make sure you change the sprite name to the the name you gave your climbing sprite

Add this code to the bottom of the switch statement

case "climb":

sprite_index = sPlayerClimb;

image_xscale=facing;

if vsp==0

subimage=0;

else

subimage=-1;

break;

}

Picture below shows where to add code

STEP 7 Cannot attack while on ladder

To disable attacking of oPlayer while climbing we will change the attack code

At the bottom of the step event of oPLayer change the attack state code by adding a check for NOT being in "climb" state

Remember when you use the != syntax that means NOT equal so you can only attack if your NOT is a climb state

//Attack state

if canattack==1 && wep=="spear" && state != "climb"

state = "attackspear";

if canattack==1 && wep=="bow" && state != "climb"

state = "attackbow";

STEP 8 Make sure you return to idle state 

This code will make sure you return to idle state at the end of each frame or step in your game Test your game you should now be able to climb up and down ladder objects if you want to add other types of ladders just make new objects like a vine or metal ladder etc then make it a child of oLadder

if move==0 && state!="attackspear" && state !="attackbow" && state !="climb"

{

state="idle";

}

STEP 10 Add global.jumpsmax variable

When your oPlayer collides with the oShoe we need to use a variable that keeps track of you gaining power up we will use a global variable called global.maxjumps that will keep track of how many jumps you can make it will be set to 1 when the game starts and once you collect the shoes it will increase to 2. Open you oStart object and add this variable to the Create Event

Your entire event should look like this now

//Variables this is your move speed and jumping distance

global.movespeed = 5;

global.jumpspeed = 20;

// New Global for Climbing Speed

global.climb_speed = 3;

//Keep track of how many jumps you can make

global.jumpsmax = 1;

STEP 11 Add jumps variable

Now open oPlayer and add jumps variable to Create Event to keep track of how many jumps you have made

Add this variable to the end of your Create Event for oPlayer

// New variables double jump

jumps = 0;

STEP 12 STEP EVENT Jump Code

We need to be able to set the amount of jumps you can perform anytime you are standing on a oBlock so we add the jumps = global.jumpsmax;

Then when you press the jump key and you have jumps to perform you can jump even in the air then we subtract one jump each time so this could make you jump as many times as you want just continue to add to the global.jumpsmax variable if it is 5 you can jump 5 times

Now add this code to the STEP Event of you oPlayer replacing the jump code with this new code

//Jumping 

if place_meeting(x,y+1,oBlock) 

{

jumps = global.jumpsmax;

}

if (key_jump) && (jumps > 0)

{

jumps -=1;

vsp = key_jump * -global.jumpspeed;

}

STEP 13 Increase global.jumpsmax variable

When you collide with the oShoe object we will increase the global.jumpsmax variable by one 

Add a collision Event to oPlayer with oShoe

Add this code to destroy the oShoe object and increase the max jumps then add oShoe to room and test your double jump skills

global.jumpsmax +=1;

with other

instance_destroy();

STEP 16 Slippery Ice Code

Open oPlayer object and we will adjust the STEP EVENT code to use new slippery ice 

Find the //React to inputs section and modify it to this I have commented to code so that you can change the local variables to make it more or less slippery or make you slower on ice than on regular oBlock objects all your jumping has been preserved by making the oIce object a child of oBlock

We are using a new function in the code called clamp this code limits a variable to stay between two numbers so in our case the hsp is limited to negative max_ice_speed and positive  max_ice_speed 

//React to inputs

move = key_right + key_left;

// --- New Local Variables for Slippery Movement ---

var on_ice = place_meeting(x, y+1, oIce);

var friction_factor = 1;

// --- Horizontal Movement Logic ---

if (on_ice)

{

    // On Ice: Apply acceleration and friction

    // 1. Acceleration (slower movement response)

    var acceleration = 0.5; // Adjust this value (e.g., 0.5 for slow start)

    hsp += move * acceleration;

    // 2. Limit Speed

    var max_ice_speed = global.movespeed * 0.75; // Adjust max speed on ice

    hsp = clamp(hsp, -max_ice_speed, max_ice_speed);

    // 3. Friction (only if player is not actively moving)

    // This makes the player slide if they stop pressing keys

    if (move == 0)

    {

        friction_factor = 0.96; // Adjust this value (closer to 1 = less friction, more slide)

        hsp *= friction_factor;

        // Stop movement if speed is near zero

        if (abs(hsp) < 0.1) hsp = 0;

    }

    else // Player is actively moving, so we keep the friction low

    {

        // Add a slight resistance even while moving

        hsp *= 0.99;

    }

}

else // Not on Ice: Use normal ground movement

{

    // Normal Ground Movement (Instant speed change)

    hsp = move * global.movespeed * movefactor;

}

STEP 17 Running Sprite

We want your character to be able to run when holding down the shift button to double your speed 

We have everything in place to make this happen remember we have a variable called movefactor that slows oPlayer down when walking through water

We can use this variable to make your player run faster as well

First lets make the new running sprite import your LPC sprite and find the running pose it will have the following:

Creating the Running Pose

Game maker does not automatically use the LPC style sheet we have to convert it to different poses

1. Click on Add Sprite Icon click load sprite and then select Edit Sprite

2. Select Image Pull Down Menu and click Import Strip Image and load your character sprite

   1. 1. Number of images and number of rows is 8

      2. Image width should be 64

      3. Image height should be 64

      4. Vertical cell offset is 41

3. Click Convert

4. If your character has a colored background select Image Erase a color to make it transparent.

5. Save as sPlayerRun

6. Select Middle Center for the sprite

STEP 18 Running Code add new keyboard check

Open your oPlayer object and add this to the STEP EVENT in the get player input section add this new key to keep track of whether you are holding down the shift key

key_run = keyboard_check(vk_shift);

STEP 19 Running Code Increase speed

Now if you hold down shift while walking you will start to run and double speed

Add this code to the STEP EVENT of oPlayer under the React to inputs section this will check if your are moving and holding down the shift key this will double your global.movespeed by multiplying by movefactor of 2

//Set Run Speed if key_run is held down

if (key_run) && move!=0

{

movefactor = 2;

state = "run"

}

else

movefactor = 1;

STEP 20 Change sprite direction while running

Under the special Blocks code change this code to allow you to change the animation direction while running

///Change States While Moving

if move==1 && canattack==0 

{

    facing = key_right;

if state !="run"

    state="walk";

}

if move==-1 && canattack==0 

{

    facing = key_left;

if state !="run"

    state="walk";

}

STEP 21 Animate Run sprite

In the Animate Character section add a new case when in a "run" state put this code inside the switch statement after the "climb" case this will animate your character when running

case "run":

sprite_index = sPlayerRun

image_xscale=facing;

subimage=-1;

break;

STEP 22 Resets State 

At the end of the STEP Event of oPlayer replace your change states to this will make sure that each frame you state will be reset based upon player input

//Resets the state at end of STEP

if move==0 && state!="attackspear" && state !="attackbow" && state !="climb" && state !="run"

{

state="idle";

}

STEP 22 Wall Jump

Adding wall jump is very easy before you Special Block code add this to enable wall jump this will check if you are colliding horizontally with a oBlock either to the oPlayers right or left and pressing the key_jump key this will give you a jump

// Wall Jumping

if (key_jump) && ((place_meeting(x+1,y,oBlock)) || place_meeting(x-1,y,oBlock))

{

vsp = key_jump * -global.jumpspeed;

}

STEP 23 Grapple hook

Now lets add a grapple hook where if you right click on a platform it will hook the block and allow you to swing or climb the grapple line