The Mound: Omen of Cthulhu Guide#

The Mound: Omen of Cthulhu is a 1-4 player online co-op first-person extraction horror game built on H.P. Lovecraft’s Cthulhu Mythos. You play an expedition member setting out from the sailing ship Tempestad to plunder a cursed jungle, and you must carry your treasure back to the ship alive while Madness warps what you see and hear.

First, what this game is not — because it contradicts a lot of casual assumptions:

• It is not an action RPG: no skill trees, no attribute points, no gear rarity tiers or random affixes.
• It is not a survival builder: no base construction, and no freely roammable open world.
• It is not a single-player level crawler: the core experience is built around team expeditions and extraction, and solo players can only bring an AI companion.
• It is not a looter in any Diablo sense: progression comes from contracts, upgrades, and unlocks, not from rarity rolls.

Basic Game Information#

The following was cross-checked against the Steam store page, the Xbox store page, and MobyGames (as of October 5, 2026):

Core Gameplay: The Expedition Loop#

Everything in this game revolves around one expedition loop — the spine for understanding it:

1. Prepare aboard the Tempestad: sign a Contract with the Captain to receive the gear for this expedition.
2. Distribute starting equipment: split weapons and supplies among the party — melee options are the hatchet and the halberd, ranged is the slow-reloading musket, and both powder and supplies are scarce.
3. Choose a region and push into the jungle: the deeper you go, the greater the threat and the reward; along the way you can find Abandoned Forts.
4. Loot and extract: bring treasure and the records of lost expeditions back to the ship — there is no minimap and no overhead radar, so team communication relies entirely on spatialized proximity voice chat.
5. Settle and set out again: trade the treasure you carried back for better gear and upgrades, upgrade your contract weapons, unlock forts as new departure points, and sign a harder contract.

A single expedition usually takes about 20 minutes — a rhythm that fits short sessions, though every “one more run” deepens the test of your judgment.

Key Structure Terms#

The Madness System: This Game’s Signature#

Madness is not a simple “sanity bar drains plus screen effects” mechanic — it is perceptual interference woven into navigation, communication, and combat decisions:

• As you push deeper, threats begin to distort your perception: hallucinations, false audio, and simultaneous interference with sight and sound make real and fake hard to tell apart.
• Each player’s Madness is independent — the anomaly you see does not appear for anyone else. This breeds a “who is lying” distrust inside the squad, and it is intentional design, not teammate error.
• The deeper the region, the stronger the Madness.
• The companion collection system is the Creature Codex: the achievements Pages Best Left Blank and The Horrors Named correspond to unlocking 7 and 13 entries respectively.

The impact on play is direct: reporting contacts, confirming routes, and judging “is something over there” all have to happen while your perception is being scrambled. The enemies sub-guide on the Chinese hub breaks down the hallucinated threats in detail.

System Requirements#

Only one requirement figure has been verified:

Full minimum and recommended specifications (CPU, GPU, storage, and so on) have not been collected from a reliable source; defer to the system requirements published on the Steam store page rather than any guesswork here.

Reception and Media Scores#

• As of October 5, 2026, the Steam page showed an overall “Mostly Positive” rating; roughly 75% of 238 reviews in the last 30 days were positive, and about 70% of all 2,175 English-language reviews were positive. Review counts roll over time, so treat the Steam page as the live source of truth.
• MobyGames lists a media average of 68% — a sample of only 4 outlets, of limited reference value.
• Two public player-progress data points: on August 13, 2026, a player unlocked the revive-50-teammates achievement Too Stubborn to Die, and on August 14, 2026, a player hit Rank 30 and unlocked Tempered by Madness. These only show the core loop supports long-term play; they are not system rules.

Guide Map#

Related Games#

• Lethal Company — a co-op horror run built on proximity voice and the same “one more expedition” pull
• Phasmophobia — co-op supernatural horror where what you hear is part of the threat
• Helldivers 2 — a 4-player co-op shooter where friendly fire and team discipline decide outcomes
• Escape the Backrooms — co-op horror about moving through hostile space and getting out alive
• Monster Hunter: World — a preparation-driven hunt loop where readiness beats recklessness

Related Rankings#

Best Co-Op Games · Best Indies of 2026 · Best Shooters

Full Guides#

In-depth sub-guides — beginner basics, combat, enemies, items and equipment, the skills question, endgame, all 25 achievements, multiplayer and cross-play, and controls — are available in Chinese on NTGame’s The Mound: Omen of Cthulhu section.

If you read Chinese, the enemies sub-guide there is the honest one: it lists only verified engagement targets and says so outright instead of padding a bestiary with guesses.