Strata - Generated Excavation Digs for GameMaker

Give the player a rock face and two tools. Strata is a generated excavation dig for GameMaker: every blow cuts the rock back a layer or two and puts stress on the face, and somewhere under it lie fossils, relics, crystals or ore. Free a find completely before the face gives way and it is theirs. Push too hard and it collapses, taking whatever is still buried with it. Pure GML.

Use it for a mining or archaeology minigame, a treasure dig behind a quest, a crafting material source, a museum or fossil-collecting loop, or a whole game of its own. Your items go in by name and come back out as what the player freed.

// Create: open a dig (the same seed always gives the same site)
my_loot = ["Gold Coin", "Raptor Skull", "Amber Drop"];
my_dig = stra_open({ seed: "quarry-east", grade: 2, rock: "limestone", finds: my_loot });
// Step: run it; when the player leaves, give them what they freed
stra_step(my_dig, device_mouse_x_to_gui(0), device_mouse_y_to_gui(0));
if (stra_closed(my_dig)) { my_result = stra_result(my_dig); stra_free(my_dig); my_dig = undefined; }
// Draw GUI: the scene is 816 x 624 at scale 1; draw it anywhere, at any scale
stra_draw(my_dig, 0, 0, 1);

What your players see

• Every dig generated from a seed: the finds and where they lie, the bedrock stones that cannot be cut, the thickness of the rock cell by cell, and the stability of the face. Stability is derived from how a careful digger does on that exact site, so no site is impossible and the grade decides how forgiving it is.
• Sixteen families of finds, all drawn by the package, each in three colourways: ammonite, trilobite, bone, tooth, amber, geode, ore, crystal, tablet, shell, fern, fish, flint point, coin, skull and potsherd. Their details (the amber's inclusion, the tablet's script, the coin's device) are re-seeded for every find.
• Eight rocks, each a different structure, not a recolour: cross-bedded sandstone, laminated shale, fossil-hash limestone, mottled clay with rootlets, columnar basalt, chalk with flint nodules, ironstone concretions, and permafrost with ice lenses. Six layers each, shown in a section column beside the face.
• The face reads its own depth: a cut cell darkens with every layer taken, the walls of a cut show the rock's own layers and cast their shadow into it, cracks spread across the face as the stress rises, and when it gives way the whole face slumps into rubble while stones fall from the top.
• A timbered frame, a stability plank that cracks and burns red, a ledger of grade, blows, stress and finds, the two tools, a tray that fills as finds come free with a glint, and a results card showing what came out. No image file is loaded.
• Arrow keys and Enter, or click a cell to strike it; Q or W swaps the pick (deep and narrow) for the hammer (wide, and twice the stress). Escape packs up with whatever is already free.

Built to plug in

• Six calls: stra_open, stra_step, stra_draw, stra_closed, stra_result, stra_free. The result names which of YOUR items were freed, whether the face was cleared, gave way or was left, and the blows and stress spent.
• Item names are read by whole words: "Gold Coin" draws a coin, "Dragon Fang" a tooth, "Ancient Glyphs" a tablet. Key a dig to a place with a word, and reopen a face your game remembers digging as worked out.
• Five grades. Measured over 60 digs each by a model of an attentive player who cannot see underground, the share that clear the whole face: 88%, 80%, 58%, 40% and 27%.
• The rules are callable on their own (pure GML, no drawing): generate, strike, the greedy digger who proves every site clearable, the sighted digger the budget is calibrated on. Every drawing function is public too, including stra_find_sprite for inventory icons of the finds.
• Opening a dig costs about half a second, once (generating the site and drawing its sheets, on our shared test machine); open behind your own transition, as the demo does. After that the face is redrawn only when a blow changes it.
• Raw, readable source with a header on every public function. THE FIELD CAMP demo room: eight test pits, one of each rock, five grades, and a collection that fills with what you dig out.

Tested

• Igor package build clean on the shipped source, and proven able to fail.
• 151 in-engine assertions on a real built exe, held to our RPG Maker MZ original run in Node: 49 generated sites compared field for field and 400 scripted blows compared cell for cell, plus both model diggers, every one exact.
• All 48 finds drawn and inked with no two families drawing the same picture; all eight rocks; a whole dig played by scripted input and checked blow for blow against the rules; a collapse; the demo room.
• A blank project that installed the package the way you will and ran the Readme's own code, with ink counted on everything it drew (41 checks).
• 164 adversarial calls against the documented functions with zero crashes.

Requirements

GameMaker 2024.14 or newer (built and tested against runtime 2024.14.4.268, VM, Windows). Pure GML; no shaders, no extensions, no DLLs, no sprites to import. Import the .yymps, put rm_stra_demo first, press Play: THE FIELD CAMP. Strata makes no sound of its own; hook your own in (pick, hammer, tool, free, collapse, done).

One commercial licence, unlimited games, no attribution required. Everything the package draws in your game is yours to ship, including on your store page and in your trailers.

Paid, from the same studio

• Strata for RPG Maker MZ ($11.99): the original, run from an event.
• Lode ($14.99): ore, gems and mineral specimens that draw themselves, for GameMaker. What the player digs out could be one.
• Unveil ($7.99): a Qix-style minigame that reveals any picture, for GameMaker.

More GameMaker systems at csaf.itch.io.

AI disclosure: the code, the cover illustration and the interface text were produced with AI assistance. Every screenshot and the GIF were rendered by the product itself. Type: Cinzel and Alegreya (SIL OFL 1.1), notices included.