What problem does it solve? Designing a balanced arena level for Jev FPS requires understanding how map layout, demon spawn placement, and movement speed interact with Jev's fixed decision rate of about nine decisions per second. This Skill guides the creation of levels that read well in 3D and expose the real performance limit of the decision loop. ## Core Features & Use Cases - ASCII Map Design: Draw arena layouts using tile characters (#, %, =, ., P, D, M, A) with rules for sight lines, spawn placement, and pillar-based flanking. - Pace Tuning: Configure demonSpeed, demon count, and tickMs to control difficulty, from a relaxed stroll to brutal waves that outpace the decision loop. - Verification Workflow: Run the toolchain check script and read .harness/verdict.json to report wave reached, kills, deaths, and shots on target. - Use Case: Create a 24x16 arena with spawns on two sides of the player start, set demonSpeed to 2.4, then watch the pane to find the wave where Jev stops clearing demons. ## Quick Start Design a Jev FPS arena level in level.json with demon spawns on two sides and demonSpeed 1.2, then run the check script and report how far Jev gets.