Working on a game

Opening a game lists every kind of file on the left, even the ones you have none of yet, and shows the selected file’s editor on the right. Changes are saved as you go (Ctrl+S saves at once). A game opened with Look inside is read-only: ✎ Edit a copy above the editor makes a copy you can change.

▶ Play Game plays the game from its title screen. ▶ Play Level plays from a level instead: its ▾ lists every way the game’s links bring the player into a level (“Level 2 at 40,12, from Level 1’s exit”), and the button plays the last one you picked, or the level whose map is open. It starts right in the level; the title and menu come after play ends.
A map shows its links as markers: cyan ways in, where the hero arrives (a star for where the game starts), and gold exits, where touching a block leads on (a flag for Game won). Drag one or nudge it with the arrow keys to move it; click it to see the map or screen at its other end and change or delete it. ＋ Exit adds one.
The + beside a kind adds one: a new file, one from the library (the free sample games on the CD, shown as pictures), one from your computer, or one made by a tool (see Making pictures, sounds and music). + Add a file… shows every kind as a grid of cards.
✎ edits a file; the red 🗑 deletes it. The .GAM file can’t be deleted.
Wherever a file is chosen (a scene’s map, a sound’s sample, a palette to view with), you see its picture; click it to choose another, or ✎ to edit it.
+ Add level scene starts a level with the last level’s palette, blocks, monsters and hero, on a fresh map of its own.
↶ Undo and ↷ Redo (Ctrl+Z and Ctrl+Y) take back changes in the editor you are in. ? lists the keys the open editor knows, and Ctrl+P finds a file or scene by name.
Download saves the whole game to play elsewhere (see Sharing your game).
A game started as ▶ Ready to play has 🎓 First steps beside Play Game: ten small jobs that make the starter your own (a color, a block, the level, the hero, a monster, a sound, a way to win…). Each ticks itself when you do it, and opens the file to do it in.

Checking a level

In a map, 🩺 opens the Level check: a bot plays the scene, tries every move from every place it can stand, and shows where it went and what players would mind (traps, dead ends, prizes in view but out of reach, and more), each with why it matters and the part of The Ultimate Owner’s Guide about it. Many have a one-click ✨ fix. ▶ Play and record adds your own play to the picture. On the start scene of the .GAM, ☑ Before you upload… is a checklist that ticks itself where the check can tell, and 🤖 Make a walkthrough… has the bot play the whole game, to watch or save as an MP4.

The DOS player and cards

The .GAM also has ▤ DOS player, to change the stand-alone DOS player’s own words, colors, frames and timings screen by screen (drag them on its preview to move them) and the extensions of its files, as 1990s authors did with a hex editor. 📝 Instruction card… and 🪧 Level card… write the game’s instructions, or a level’s name, goal and hint, from a few lines of yours and the game’s own keys.

Your own AI

✦, beside the open file’s name, opens the Assistant: an AI you set up yourself (⚙ Settings → AI setup…, with Ollama on your computer or an OpenAI key) that can look at the game, change it, run the Level check and suggest what to do next. Every change can be undone, and you can have it ask first or only look. An AI app on your computer that speaks MCP can do the same: choose Use an AI tool on this computer instead (MCP)… in the Assistant.

Open this in the Guide · Game-Maker: Sandbox Edition