+H

Introduction to new players

+H is a roleplaying game of modern science horror by Petri Leinonen. Players take on the roles of a highly competent field team working for New Horizons, a massive biotechnology corporation. The game is mission-based and centers on the team's "First Encounter" with the shadow biosphere—a hypothetical "Life 2.0" that isn't carbon-based but has always existed alongside us, and is only now becoming dangerously active. The game's core themes explore the horror of encountering the truly unknown, how a group forms (or breaks) under extreme pressure, and the terror that skilled professionals experience when faced with situations for which they could not have prepared.

The game's mechanics are derived from Powered by the Apocalypse (PbtA) engines but have evolved significantly into their own unique, mission-focused structure. It's not a typical PbtA hack; rather, it uses PbtA techniques alongside mechanical innovations from story games and draws heavily from the Nordic immersion tradition. This blend creates a distinctive playstyle focused on getting to know the player characters deeply through their actions. Gameplay is driven by conversation, with rules and dice (2d6) intervening only when the narrative triggers specific "moves". A standout feature is that players receive new rule cards as the game progresses, gradually opening up new actions and ways to interact with the unfolding story.

+H was born from a wide array of influences, beginning with the author's fascination with the shadow biosphere concept from David Toomey's book "Weird Life". While its mechanical base is Apocalypse World, one of the game's first goals was to bring fresh perspective to the classic horror RPG Call of Cthulhu. It also draws specific ideas from other PbtA games, such as Dungeon World's group-vs-threat focus, Night Witches' situational moves, and Tremulus's approach to PbtA horror. Beyond the PbtA family, the game also cites Dread, Fate Core, Blacksad, and the Orpheus RPG (with its episodic story structure) as major inspirations.

How +H Game Mechanics Work

The +H roleplaying game uses a heavily modified Powered by the Apocalypse (PbtA) engine. Its mechanics are designed to be conversational, with rules and dice rolls only occurring when a character's action in the story triggers a "move".

The system is built to mirror the game's core themes. For players, the ruleset expands as the mission descends into chaos. For the Game Master (GM), "Threat Paths" provide a narrative structure to pace the horror, building suspense from mystery to a deadly confrontation.

Player Mechanics in +H

For players, the progressive mechanics simulate the experience of a highly competent professional slowly realizing their skills are useless against an unknown, alien threat.

What are Progressive Mechanics?

Players do not start with all the rules. Instead, they receive new rule cards at specific milestones during the "Ensikohtaaminen" (First Encounter), mechanically reflecting the situation's escalating danger.

1. Saapuminen (Arrival): At the start, players have only one broad move: toimi (act). This move is forgiving and represents their general professional competence on what seems like a routine mission.
2. Tehtävän suorittaminen (Mission Execution): As the mission progresses, players receive new moves that replace toimi: etene tilanteessa (advance in a situation), sitoudu väkivaltaan (commit to violence), and tutki faktoja (investigate facts). They also gain Lähestymistavat (Approaches), a mechanic that defines a character's "favored" and "challenging" styles, which alters the die roll needed for success.
3. The Situation Worsens: After making four moves, the simple toimi move is removed from play. Players now gain moves for teamwork, such as auta (help) and estä (hinder), as well as their first unique Specialization move.
4. The Breaking Point: After making six moves, players unlock their Piirteet (Traits) and the tahto toimia (Will to Act) move. This allows them to add dice to a roll by showing how a trait helps, or gain a resource by taking fewer dice and showing how a trait hinders them.

How does damage work in +H?

When a character is harmed, they receive Säröt (Cracks or Flaws) instead of losing hit points.

Narrative Damage: Säröt are narrative traits that describe the harm.

Physical, Mental, and Social: A "crack" can be physical (e.g., "murtunut jalka" - broken leg), mental (e.g., "kauhuissaan" - terrified, "uupunut" - exhausted), or internal (e.g., "turvaton" - insecure).

Character Death: A character dies when they receive a new särö but have no space left to mark it on their sheet. At this point, they make one more "Death Move" that changes the situation for everyone still alive.

How do players interact with the Shadow Biosphere?

Player moves are intentionally designed to be used on people and known situations.

Ineffective Moves: If a player tries to use a move like sitoudu väkivaltaan (commit to violence) against a shadow biosphere entity, it does not trigger a roll.

Narrative Consequence: The GM simply describes what happens based on the alien nature of the entity.

The Core Horror: This mechanic is central to the game's horror. It strips players of their mechanical power and forces them to feel the same dread and inadequacy as their "competent" characters, whose skills are suddenly useless.

Game Master (PJ) Mechanics in +H

For the Game Master (Pelinjohtaja, or PJ), the mechanics provide a robust framework for pacing suspense and reacting to the players without a pre-written script.

What are Threat Paths (Uhkapolut)?

This is the GM's primary tool for preparation and pacing. Instead of a script, the GM prepares 3-4 "Threats" (e.g., the alien entity, a human antagonist, the environment). Each threat has a 4-step path it advances along during the game.

Esittele (Introduce): The threat's presence is merely hinted at. The GM gets "marks" on the path just for describing clues or signs of the threat. The threat is not yet actively harmful.

Ennakoi (Foreshadow): The threat is revealed to be actively dangerous. The GM gets marks for showing the consequences of the threat (e.g., a body, a sabotaged machine).

Paljasta (Reveal): The threat becomes a concrete, active danger and unlocks its own unique, harmful "moves" for the GM to use.

Finaali (Finale): The threat unlocks its most dangerous and "cruel" moves, designed for the game's climax.

How does the GM trigger the Finale?

The GM has narrative control over the game's climax, the "Finaalivaihe" (Final Phase).

Condition: The GM can only trigger the finale after at least one Threat Path has reached Step 3 (Paljasta) and the GM has used one of that threat's new moves.

Effect: When the finale begins, all active threats on the table immediately gain a "mark," escalating them and unlocking their most dangerous abilities.

What are the GM's Principles (Periaatteet)?

The GM is guided by a set of Principles (Periaatteet) that define how to run the game and maintain its specific tone. Key examples include:

Ryhmänjäsenet osaavat asiansa (The group members are competent): Never make a player roll to see if they can do their job; roll to see what happens when they do it.

Älä nimeä varjobiosfäärin ilmiöitä (Do not name the shadow biosphere phenomena): Let the players name the alien things they encounter.

Varjobiosfäärin kohtaaminen on... harha-askeleen päässä kehokauhusta (Encountering the shadow biosphere is... a misstep away from body horror): Always be ready to show the gruesome physical effects of the unknown.