The Petrichor Protocol

Risk of Rain 2 was never meant to be played the same way twice. This is the mod that makes sure it never is.

The Petrichor Protocol is a single, self-contained challenge engine that quietly rewrites the rules of every run. Not with new characters or new items, but with something rarer: the feeling that the game itself is alive, reacting, and occasionally out to get you. One run the enemies are giants and every kill rains gold. The next, a hunter with your scent stalks you across the stage while the teleporter zone shrinks around your feet. The run after that, gravity gives out mid-fight and you are suddenly floating through a meteor storm you did not ask for.

None of it is scripted. All of it is real.

What it actually does

Under the hood, the Protocol is a stack of modular systems, each one a real modification to how the game behaves. You turn them on and off freely, and the mod keeps score.

Size and Scale. Shrink your survivor into a nimble gremlin, or blow the enemies up into lumbering titans. Every combination changes how you move, aim, and survive.
Mutations. Ordinary enemies spawn twisted: frenzied, volatile, colossal, or gleaming with treasure. Bosses can split, shield, or grow into stage-filling monstrosities.
Environment and Events. Stages draw curse cards that hold for that stage alone. Meteor storms roll in. Every few minutes a world event interrupts everything: a bounty hunter, a supply drop, a mutation surge, a sudden titan. The teleporter itself can turn hostile, shrinking or charging you a price in blood.
Items and Loot. Curate your drops into deliberate challenge builds: no healing, glass cannon, commons only. Or let your items turn unstable, transforming stage to stage so your build never sits still.
The Randomizer. Do not want to decide? Let the Protocol roll you a fresh run at the risk level you choose, from a light dusting of chaos to a full nightmare.

The Risk Score

Here is the heart of it. Everything you enable adds to a Risk Score, and the higher that score climbs, the more the game pays you back in gold and experience. Chaos is not just punishment. It is a bargain. You are always deciding how much danger you can turn into reward, and the mod tells you exactly where you stand: Casual Chaos, Risky, Brutal, Nightmare, or the deep end, Apocalypse.

Every run is also given a generated title from whatever you had active. "David vs Goliath." "Tiny Apocalypse." "Cursed Convergence." Your runs stop being a blur and start being stories you can name, remember, and share.

Built honestly

This mod has a rule it does not break: it only ever connects to real, verified game mechanics. Nothing here is a fake effect or a cosmetic bluff. The meteor storm is the game's own meteor storm. The teleporter modifiers use the same systems the game uses. If a feature could not be built on something real, it was cut rather than faked. What you see happening is genuinely happening.

Everything is configurable in-game through Risk of Options, cleanly organized into collapsible categories so you can build the exact experience you want in seconds, then live-tweak it between runs. Install it alongside the standalone Dileppy mods and the Protocol takes the wheel automatically. No conflicts, no double effects.

Who this is for

If you have hundreds of hours in Risk of Rain 2 and you are chasing that first-time feeling again, this is for you. If you make content and you want every run to have a built-in hook and a name worth putting in a title card, this is for you. If you just want to flip a few switches and watch the game become gloriously, dangerously new, this is very much for you.

Petrichor is the smell of rain after a long dry spell. That is the idea. Something familiar, suddenly fresh again.

Turn it on. See what the sky brings.

Everything in the box

Every feature has a master toggle. Enemy and Boss Mutations are ON by default; everything else starts OFF - flip on exactly the experience you want, or set a Preset and let it compose one for you.

Feature	What it does	Stars
Enemy Mutations	Giant / Tiny / Frenzied / Volatile / Treasure enemies	4
Boss Mutations	Colossal / Frenzied / Shielded / Volatile / Splitting bosses	3
Curse Deck	Every stage draws a curse card that rewrites its rules	3
World Events	The Hunt, Supply Drop, Mutation Wave, Titan Arrival, Gravity Failure, Blood Frenzy	3
Environmental Hazards	A real Glowing Meteorite-style meteor storm	3
Enlarged Enemies	Giant enemies: stronger, slower, better loot	3
Stage Personalities	Low Gravity, Treasure Storm, Monster Migration, Boss Territory	2
Teleporter Rules	Shrinking Zone, Blood Zone, Enemy-Favored Zone, Overcharged	2
Item Diet	No Healing, Glass Build, Speed Demon, Common Only, One Rarity Per Stage	2
Loot Mutations	Volatile Items (transform each stage), Empowered Duplicates	2
Challenge Contracts	Optional per-stage objectives (Kill the Titan, Speed Clear, No Healing, Elite Hunt, Stay Inside, Pacifist Start) with bonus rewards	2
Enemy Swarm	Occasionally floods a stage with many copies of one enemy type	3
Shrunken Survivor	Tiny you: weaker, faster firing, camera pulled in	2
Bigger Bullets	Bigger bullets = more damage, more area	2
Shrunken Enemies	Tiny fast enemies, less loot	1
Enlarged Survivor	Giant you: strong, slow firing, reduced loot	1
Combo System	Named bonuses for matching features	1
Randomizer	Roll a random modifier set: Light Chaos, Balanced, Nightmare, True Random	-
Run Titles	Auto-generated shareable name for each run	-
HUD	On-screen Risk Score, tier, and run title panel	-
Notifications	Master switch for all Protocol chat feedback	-
Challenge Presets	One setting, one curated experience	-

Configure in game with Risk of Options

Install Risk of Options and every Protocol setting appears in the in-game settings menu, sorted into clean collapsible categories - toggle features, change tiers, and tune multipliers without touching a config file. (Without it, everything still works through the standard BepInEx config.)

Presets

Set SelectedPreset (config or Risk of Options) and the Protocol composes an experience for you:

DavidVsGoliath - tiny you, giant enemies
KaijuMode - giant you, tiny swarm
GremlinMode - microscopic fast enemies everywhere
BulletHellLite - big bullets, big enemies

Prefer single features? They're standalone mods too

Every Protocol feature is also published as its own mod under Dileppy - grab just ShrunkenSurvivor, just BiggerBullets, whatever you want. Run a standalone next to the Protocol and the Protocol takes precedence automatically - the standalone goes dormant, no double effects, and the Risk Score still counts it.

Multiplayer

The host's Protocol defines the run. Singleplayer is the primary supported mode.

Changelog

2.14.0 - IMPORTANT FIX: the mod now correctly lists HookGenPatcher as a dependency. It always needed it, but never declared it - so installing the Protocol on its own (without other mods that happen to pull it in) could leave it silently failing to load. Mod managers will now install it for you automatically. Camera framing is real again: the Shrunken/Enlarged Survivor camera options had quietly done nothing, and now genuinely move the camera to match your size, using the game's own camera system and touching only the camera distance so everything else behaves normally.
2.13.1 - Future-proofing complete: the mod no longer uses ANY deprecated Risk of Rain 2 API, so it should keep working through upcoming game patches that remove them - including the item-drop system that Item Diet depends on. Also fixes a latent bug in Volatile Items: when swapping a held item it now counts, removes and grants strictly permanent copies, so a temporary stack can no longer cause the swap to hand back more items than it took.
2.13.0 - Big efficiency pass. The mod now only ever does work for the features you actually have switched on: every game event is dispatched to just your enabled features instead of every feature that could theoretically want it, rebuilt live the moment you flip a toggle. With everything off, the mod does essentially nothing at all. Also began future-proofing against Risk of Rain 2 API deprecations so the mod keeps working through upcoming game patches - no behaviour changes.
2.12.0 - Tracer scaling now actually works. ScaleTracers had been advertised but silently did nothing; Bigger Bullets now genuinely grows the tracer and muzzle effects of your own enlarged shots, using the game's own effect-scaling field, and only for that shot - nothing else in the world is touched. Performance: the effect hook it needs is the hottest in the game, so it is now attached ONLY while tracer scaling is switched on - if you don't use it, it isn't installed and costs nothing. Also fixed the Randomizer silently ignoring its minimum risk: a Nightmare roll could land at Risky. Modes now guarantee their band. Two hooks that were never released on unload are now cleaned up.
2.11.4 - Clearer loot feedback. The EMPOWERED message now spells out exactly what happened - you held enough copies of a common item, so you were granted one free bonus stack of it (with the new count shown) - instead of the vague 'grew stronger'. The Loot Mutations descriptions were reworded to match, and all loot notifications now respect the Notifications master switch.
2.11.3 - Stability pass. Fixed a bug where gravity could stay lowered after a run ended mid-effect (a Gravity Failure curse or world event when you died or quit), leaving the whole game low-gravity until restart - gravity now always restores at the start of a run. Also hardened reward scaling against extreme values so gold/XP can never overflow to an absurd number.
2.11.2 - Performance fix. The gold Treasure-enemy glow was keeping a per-frame update alive for a few seconds after it finished and using costly real-time lighting; it now stops the moment the glow is applied and uses a cheaper light, which removes a frame-rate drag that built up when several treasure enemies were on screen.
2.11.1 - Fixed the Risk of Options menu page order: the Presets page now correctly appears first instead of in the middle. (Risk of Options orders pages by registration sequence, not the number label, so options are now registered in category order.)
2.11.0 - Cleanup and clarity pass. Every preset, combo, and run title now has a globally unique name (no more overlap between the master presets, the combo bonuses, and generated titles). Trimmed the config file: all the scattered per-feature announcement toggles now route through the single Notifications master switch, and the combo sub-toggles were folded in - about a dozen fewer settings to wade through. For players who edit the config by hand instead of using Risk of Options, the SelectedPreset entry now explains exactly what to type to configure the whole mod at once.
2.10.1 - Menu polish: the Presets page is now 0. Presets (Start Here) at the very top of the Risk of Options menu, with the other categories renumbered 1-7 (Protocol Core moved to the end).
2.10.0 - Challenge Presets rebuilt into the mod's master control panel, on its own Presets (Start Here) menu page. Each preset now has 100% control: selecting one instantly turns every gameplay feature on or off to match, and reports the resulting Risk Score. Ten presets from Clean Slate to Total Chaos, each with a thorough description of what it does. Interface options (HUD, notifications, titles) are left untouched.
2.9.1 - New: Enemy Swarm - a stage can occasionally flood with ~10 copies of a single enemy type for a themed encounter (off by default). Refinements: Size Roulette now scales enemy health with size, so big enemies are genuinely tanky and hard to beat rather than just large; and the Kill the Titan contract now spawns a real elite with heavy HP and damage, making it a considerable target worth the reward.
2.9.0 - Phase 5 begins with Challenge Contracts: each stage can offer one optional objective - Kill the Titan, Speed Clear, No Healing, Elite Hunt, Stay Inside, or Pacifist Start - and completing it pays a bonus reward. Ignoring a contract costs nothing. Off by default. Session-only: contracts resolve within a stage and nothing is saved to disk.
2.8.1 - Reset to Default now guarantees a true clean slate: it turns every gameplay feature off (previously features that shipped on-by-default stayed on), while leaving the HUD and notifications up. The on-screen HUD panel moved to the empty top-center band so it no longer overlaps the money and level readout.
2.8.0 - New feature: Size Roulette. Instead of locking one size, it randomizes every survivor and enemy to a random shrunk-or-enlarged state, re-rolling either on each teleport or mid-stage on a timer - your size (and theirs) can change while you are still fighting. Also adds a Reset All Settings To Default button in the Risk of Options menu (Protocol Core section), so you can wipe a complex setup back to a clean slate - every feature off - and rebuild from scratch.
2.7.2 - Every option in the Risk of Options menu now has a full, self-contained explanation, so clicking any toggle or slider tells you exactly what it does and what its value means - no more guessing from a bare label.
2.7.1 - Fixed the Risk of Options menu showing multiple identical Enabled toggles with no labels. Every option now has a clear name - each module's master toggle reads as the module's name (Run Titles, HUD, Notifications, etc.) and secondary options are labeled by what they do.
2.7.0 - Performance and menu polish. The Risk of Options menu is now organized into collapsible buckets (Size & Scale, Mutations, Environment & Events, Items & Loot, Presets & Randomizer, Interface & Feedback) instead of one long list - no settings moved, only how they're grouped. Under the hood, event dispatch was rebuilt so each game hook only notifies the modules that actually use it, rather than all modules every time - this removes the per-frame overhead that was causing slowdown.
2.6.0 - Phase 4 polish layer: Randomizer (roll a fresh modifier set by risk band), Run Titles (every run gets a shareable generated name like Tiny Apocalypse), an on-screen HUD panel showing Risk Score, tier and title, and a Notifications master switch.
2.5.0 - Phase 3 build-variety layer: Item Diet (curated drop rules - no healing, glass cannon, common-only, and more) and Loot Mutations (Volatile Items transform stage to stage; Empowered Duplicates reward heavy white-item stacks). Both off by default - opt-in challenge modes.
2.4.1 - Treasure enemies now glow gold - a gold light plus an emissive tint on the model - so they're recognizable on sight.
2.4.0 - Three new modules: World Events (timed events every few minutes: an elite hunter with a bounty, real chest drops, mutation surges, titan enemies, gravity failure, blood frenzy), Stage Personalities (each stage can roll an identity), and Teleporter Rules (built on the same zone mechanics as the Focused Convergence item). Features with no real basegame mechanic to connect to were deliberately cut rather than faked: Dense Fog, Nightfall, and Moving Zone.
2.3.0 - Precedence fixed: when a standalone Dileppy mod is also installed, the Protocol now takes priority and the standalone goes dormant.
2.2.0 - Environmental Hazards rebuilt to spawn the game's own vanilla meteor storm object instead of a custom simulation. Hazards with no real basegame equivalent were removed.
2.1.1 - Risk of Options integration now uses a proper soft dependency (direct typed calls) instead of reflection.
2.1.0 - Two new modules: Curse Deck and Environmental Hazards.
2.0.0 - The Protocol became the complete experience: every Dileppy feature built in with master toggles, Risk of Options in-game configuration, native presets and combos.
1.0.0 - Detector release: Risk Score, tiers, reward scaling.

Created by Dileppy. Built with care for the Risk of Rain 2 community.