Prospecting Drill

This mod was designed for no-ore-patch challenge runs. It adds a set of prospecting drills that spawn ores based on input.
Drills consume ore-sample templates, detect the ore based on the chemical composition of the given sample and grow matching ore patches in a ring around themselves. There are three drill tiers, three sample tiers, quality-aware yield, and dynamic per-ore generation that picks up vanilla, Space Age, and modded ores automatically.

How it works

Find the Remnants, which are special rocks that stand out in the world. They will unlock the recipe for the 4 basic ores and provide samples for then.
Research the base Prospecting tech to unlock the MK1 drill. Each ore has its own three-tier research chain (Prospecting: <ore> (T1/T2/T3)) that unlocks the matching sample recipes. Tier 2 also unlocks purification for that ore, and gates on tier 1; tier 3 gates on tier 2.

Craft a sample for the ore you want, then drop the sample into the input slot of a Prospecting Drill. Every cycle, the drill picks a random tile in its ring and either spawns a new ore patch there or adds to the existing one. Over time, the ring fills and the patches grow.

The drill auto-selects its recipe from whatever sample you drop in, like a furnace. Mass-route any mix of sample ores and sample qualities to the drill: it processes whatever arrives. Please note that it's not a very good idea to just dump every sample you have in the same drill, unless you like sorting mixed ores.

Drill tiers

Sample tiers and yields

Purification is its own step: 1 ore plus 10 water gives 1 purified-ore in a chemical plant.

Quality

Sample quality multiplies the per-cycle yield linearly: multiplier = 1 + 0.3 * quality_level. Normal is 1.0, uncommon 1.3, rare 1.6, epic 1.9, legendary 2.2. The drill always spawns normal-quality ore (engine limitation on resource entities), but the amount is bigger.

Quality propagates through the vanilla quality system, so a rare assembler making samples will produce rare samples, which feed back into the drill for bigger yields. If you have quality modules available and no mod to add drawbacks to them, they are very useful at increasing the yield of each ore. I tested this with a mod that adds more quality tiers and things worked fine (except the highest quality being slightly overpowered).

Bootstrap: remnants and the extract recipe

Rare worldgen structures called Prospecting Remnants spawn on configured surfaces. Mining one gives 1-2 random T1 samples (weighted by what is native to that surface), plus a small chance of an extra non-native sample and an even smaller chance of a free MK1 drill.

Each sample-t1 also has a no-tech-required Extract <ore> from sample recipe that converts 1 sample back into 1 raw ore. That works in handcraft from the start. So a no-ore-patch challenge can bootstrap: find a remnant, mine it for samples, decompose a few samples into ore, smelt those to reach automation science, then research Prospecting normally and use the rest of your samples in a drill.

Settings

• Remnant spawn surfaces (comma-separated). Default: nauvis. Add other vanilla planet names or modded surface names as needed.
• Remnant spawn density per tile. Default ~0.0003 (about one per 3-4 chunks).
• Auto-generate samples for modded ores. On by default. Turn off for vanilla and Space Age only.

Compatibility

Tested with vanilla Factorio 2.0, Space Age and with Exotic Space Industries: Remembrance. The mod scans every ore-bearing resource at load time, so heavy ore mods like Bob's Ores or Krastorio should pick up sample generation automatically (though Krastorio would likely not work at this point, since it's not compatible with Space Age). Modset-aware: if an overhaul mod oreswaps vanilla resources (e.g. Remembrance renaming iron-ore's mined output to ei-poor-iron-chunk), the loot tables and recipes follow the swap.

The hardcoded planet-to-ore mapping is vanilla and Space Age only; modded planets default to "no native ores" (remnants on those surfaces roll only the 1% off-planet bucket). The mapping can be edited in the mod's lua tables.

ESI:R 3x3 ore patches work, but are still the same size and you still need Deep Drills for them, they may not be the best unless you get them to a high ore count before starting to mine.

Known limitations

• Spawned ore in the ring is always normal quality, regardless of sample or drill quality. This is an engine constraint on resource entities, not a design choice.
• The MK3 drill accepts speed and efficiency modules. Productivity and quality are locked out: productivity by design (see Balance below), quality because spawned ore can never carry quality (engine constraint).
• For resources with multiple solid mining products, the mod uses the first product.
• One ore type per ring at a time. If you switch sample types (e.g. coal then stone) while the ring still has the previous ore, the drill will sweep every ring tile and place on any matching or empty spot. If the entire ring is occupied by a different ore or by player buildings, the new sample is consumed without producing ore. Mine the ring clear before switching, or place a fresh drill for the new ore.
• Vanilla mining drills shut off when they fully deplete a resource patch, and stay off even if a Prospecting Drill regrows ore on the same tile. Re-toggle or replace the mining drill to re-engage it. Still thinking on a way to fix this without manual interaction.
• No-ore-patch challenges bootstrap via the Extract <ore> from sample recipe rather than the tech-trigger system. The reverse recipe is always enabled and converts a sample back to raw ore, so even modsets that aggressively re-gate tech prerequisites can still use remnant samples to reach normal science.

Balance and cheating notes

• You can, technically, never leave Nauvis, as you can find rare samples of every modded ore that can be mined, but getting the reseach for them would likely make this extremely slow to achieve.
• Ore yield is fully determined by sample tier and sample quality. Modules only affect cycle time (speed) and energy use (efficiency). All recipes in this mod set allow_productivity = false, and the MK3 drill's allowed effects exclude productivity. The reason is that productivity stacks brutally across long chains: a single productivity bonus on the drill alone could turn 2 ore in into ~50 ore out per cycle, and some mods may end up with hundreds of plates from those 2 ores, which seems way too broken.
• The Extract from sample recipe (1 sample-T1 to 1 raw ore, always available, no research) is the intended bootstrap for no-ore-patch starts. Some players will see it as a soft cheat. It is, by design. If you want a stricter run, simply don't craft it.
• Auto-generate samples for modded ores may pick up debug or sandbox resources from some mods (for example infinity-ore or testing variants). Turn the setting off if you want vanilla and Space Age only.
• Remnant spawn density is a knob, not a balance recommendation. The default 0.0003 is what the mod was tuned around. Higher values can flood worldgen quickly.

License

MIT