OSE Advanced Fantasy
OSE Advanced Fantasy is a rules-lite OSR retroclone expanding Classic Fantasy with Advanced D&D options. Race-class separation, additional classes, and expanded magic bring 1E depth to B/X simplicity. Modular, clean presentation makes it ideal for players wanting classic complexity without the cruft.
OSR/B/X + 1E lineage • d20 roll-under • 3-6 + GM • Low prep • Rules-lite • 2-4h sessions
OSE Advanced Fantasy presents a classic high-fantasy world of dungeon delving, wilderness exploration, and stronghold building. The implied setting draws from decades of D&D tradition—mysterious ruins, perilous forests, and ancient magic waiting to be uncovered.
Theme and Setting
Unlike the streamlined Classic Fantasy, Advanced introduces the complexity of separated race and class, enabling elven wizards, dwarven fighters, and halfling thieves as distinct combinations. The tone embraces pulp fantasy adventure where danger is real, treasure is the primary reward, and player ingenuity trumps character build optimization.
How Play Feels
The game uses the familiar d20 roll-under mechanic for ability checks, attacks, and saving throws. Character creation offers significantly more options than Classic Fantasy: nine additional classes (acrobat, assassin, barbarian, bard, druid, illusionist, knight, paladin, ranger), separated race and class, and expanded spell lists including 6th and 7th level magic.
What Makes It Distinct
The presentation follows OSE's signature "control panel" layout—each topic spans facing pages for instant reference. Encumbrance is tracked by item slots rather than pounds.
Where It May Not Fit
You mainly want short standalone sessions with minimal carryover You want the system to stay almost invisible at the table.
What this game is about
A strong fit for groups that want fantasy adventure with a clear play identity, with class-based helping define the experience.
Structured data and an explicit decision profile JSON document are available for remote agents.