GameMaker to Godot: rebuild your GML game in Godot 4

The first thing that breaks in a GameMaker port is speed. A GML Step event runs once a frame, so hsp = 4 means four pixels a frame and grv = 0.3 means a third of a pixel a frame, every frame. Godot's _physics_process hands you delta, the seconds since the last tick, and its physics speaks in pixels per second.

So every number in a Step event gets multiplied by the room speed, once for a speed and twice for an acceleration. At a room speed of 60, a walk speed of 4 is 240 pixels a second, a gravity of 0.3 is 1,080 pixels a second squared, and a jump speed of 7 is 420 pixels a second. Miss one and the game runs at the wrong speed in a way that is hard to see until you play both.

We checked that arithmetic on a small GameMaker platformer rebuilt in Godot 4.7.2: walk, gravity, a jump and a coin. The Godot version walked at exactly 240 pixels a second and its jump peaked at 85.2 pixels, against 85.1 for GameMaker's own frame-by-frame jump, and the coin scored. The numbers were right because they were converted, not copied.

More on this: A GameMaker Studio alternative for people who never wanted to write GML

An object becomes a scene with a script. Its Create event becomes _ready, Step becomes _physics_process, a Collision event becomes an Area2D's body_entered signal, an Alarm becomes a Timer node, and Draw becomes either a Sprite2D or AnimatedSprite2D child or a _draw() override. instance_create_layer becomes instantiating a scene and adding it to the tree; instance_destroy becomes queue_free.

The place_meeting loop, the one that inches a player pixel by pixel until it touches a wall, is what CharacterBody2D's move_and_slide() does for you, floors and slopes included. global variables become properties on an autoload, with() becomes a loop over a group, and parent objects become inherited scenes or a shared script.

Both engines put the origin at the top left with y pointing down, so positions from a room carry across unchanged.

GameMaker Studio 2.3 and later keep a project as readable files: the .yyp, a .yy JSON file per object, sprite and room, and a .gml file per event. Rooms list their instances and layers with positions; sprites are folders of PNG frames with their origin and speed. The AI reads all of it, so a level is rebuilt where it was.

Sprites become SpriteFrames for an AnimatedSprite2D, with the same frames and speed. Tile layers become TileMapLayer nodes from the same tileset image. Sounds copy across. Art you made is yours to move; Marketplace assets come under their own licences.

Put the GameMaker project where Flockbay can read it and open a new game. Tell Flockbay what you are bringing and how it plays. It reads the objects, events and rooms, writes a brief of what it rebuilds first and what changes on the way, and builds nothing until you approve it.

It rebuilds each object as a scene, converts every per-frame value at your room speed, imports the sprites and tiles, and checks its own work by playing: input events, stdout, the debugger and viewport captures. Then you play both versions and say what feels off. Feel is where a port drifts, and GameMaker games are often tuned to the pixel.