Arrhenius
Core RulebookBest For
Groups who want a survival-focused science-fiction campaign where characters cross frozen ruins, manage limited equipment, and resolve fights on a tactical grid.
Core Mechanic
For skill checks, roll a d20 and add the two relevant Talents plus the applicable Education score. A total of 21 or higher succeeds. Before a non-damage d20 roll, Luck Points can add +1 each to its bonus.
Ordinary checks use a fixed d20 target. Character building, tactical combat, and survival rules create several procedures that interact at the table. Learning how those layers affect one another is the main study load. The straightforward core keeps that load modest relative to denser rules-heavy systems.
- Free to tryQuickstartA free starter you can actually play
- Get it nowSold newIn print or as a legal PDF
- ✓IndexFind any rule by page number
- ✓GM guidanceA chapter on how to run the game
- ✓Examples of playRules shown in action at the table
- ✓Quick referenceCheat sheet or summary tables
- ✓Cross-referencesRules point to each other by page
5 of 5 book tools found in the core book
Highlights
Frost Points turn prolonged exposure to subzero conditions into resilience checks, so shelter and protective gear shape expeditions. The optional Tuning Session assigns Talent scores through a short character-memory scenario, tying early choices to the resulting build. Combat uses a 2-meter grid with optional Perks that award attack bonuses for flanking or high ground.
Considerations
Exposure to subzero temperatures triggers a Resilience check every 20 minutes of real table time and failure costs one Frost Point. Broad equipment archetypes rely on the Dungeonteller to define the specific items characters encounter. Combat resolves each attack through opposed rolls before damage is rolled.
Rules license All Rights Reserved
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