Touchpaper - Elemental Surfaces for GameMaker

Touchpaper gives the ground a state, and lets fire, water, frost, oil, lava and lightning argue over it. Every cell of your map carries a material and five numbers - heat, wetness, charge, fuel and flags - and the materials react. Dry grass catches and the fire crawls with the wind, leaving charred ground and ash. A soaked strip is a firebreak. Cold freezes a river into a sheet the player can walk on, and heat thaws it back. Light one end of an oil spill and the whole trail runs. A spark earths through water, wet ground and metal. Lava lights what it touches, boils the water beside it and crusts to stone where it is quenched.

None of it is scripted. There is no fire event and no ice event: the rules are properties of the materials, so combinations you never planned still work.

All of it is drawn by the product

The ground, the flames, the light, the smoke, the ice and its cracks, the lava crust and the lightning are generated at run time from primitives. There is no sprite sheet and no sprites/ folder in the package. The field is drawn as one composed surface, not stamped tiles: patterns run on across cells, neighbouring materials blend at a soft ragged edge, and the orange of a fire is light that spills onto the grass ahead of it.

• 11 materials: stone, grass, wood, sand, water, snow, mud, ash, oil, lava, metal
• 11 states: dry, wet, frozen, burning, scorched, ashed, charged, steaming, glassed, molten, glowing
• 52 looks the ground can actually reach, counted by driving the model through every input rather than multiplying 11 by 11. The atlas above draws exactly those 52, each simulated into place.
• Night and caves: one call darkens the scene and every fire, lava pool and discharge lights the ground around it.

Made to drop into a game

field = tpr_field_create(40, 22, 32);
tpr_fill(field, "grass");
tpr_rect(field, 27, 0, 29, 21, "water");
// Step
tpr_update(field);
if (mouse_check_button_pressed(mb_left)) tpr_ignite_at_point(field, mouse_x, mouse_y, 1, 255);
// Draw
tpr_draw(field);

• Gameplay hooks: tpr_hazard(field, x, y) tells a character whether it stands in fire, a discharge, on ice or in water; tpr_is_walkable knows frozen water can be crossed.
• Saving: the whole field to one compressed string and back, validated on load, so a burnt forest stays burnt.
• Performance by design: one cached ground surface repainted per cell only where the look changed, on a per-frame budget; flames and smoke are sprites the product builds once at start-up.
• Pure GML, no extensions, no shaders. Everything namespaced tpr_. Built and tested on runtime 2024.14.4.268.

Tested, and you can check

Run the project with -selftest: the in-engine suite reported 125 assertions, 125 passed on the build that shipped. Separately, the shipped package was imported into a blank GameMaker project and used as the Readme documents it, and 176 hostile calls against the documented API crashed nothing. The runnable demo room has five scenes - Meadow, Frozen Lake, Oil Trail, Storm Crossing, Forge - and six tools to play with.

Also from Core Systems Asset Factory

• Touchpaper for RPG Maker MZ - the same idea for MZ maps.
• Affliction - status effects and ailments with generated icons; pair it with burning and charged ground.
• Welkin - the sky and weather above the ground Touchpaper draws.
• Barrage - bullet patterns whose projectiles draw themselves.

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AI disclosure: this package's code and its generated artwork were written with AI assistance. It contains no audio and no narrative text. The cover is a generated illustration; every other image on this page was rendered by the product itself.