Ready or Not: How to Create a Custom Mission with Mission Editor

Open Mission Editor in its supported session context

Open Mission Editor from the main menu. The release notes support singleplayer and a multiplayer Friends-Only lobby. The feature modifies variables in an existing mission; it is not described as a tool for building a new level’s geometry from scratch. [1]

Start with the existing mission whose gameplay you want to modify, then tailor its variables through the editor’s Basic and Advanced tabs. [1]

Steps

1. Open Mission Editor from the main menu. [1]
2. Use singleplayer or a Friends-Only multiplayer lobby for the edited mission. [1]

Adjust the Basic AI variables for the encounter

The Basic AI tab exposes SWAT health, accuracy and fire rate; suspect health, starting morale, stun resistance, accuracy and fire rate; and civilian health. Pick the category that matches the behavior you want to change. Civilian health is distinct from suspect health, and SWAT effectiveness has its own controls. [1]

Set the player’s Basic survival constraints

The Basic engineering options include limited bandages and Damage Cap. Damage Cap is specifically the maximum damage received by the player in one hit, so it should not be read as the player’s total health setting. [1]

Player Health appears under Advanced options, alongside an expanded bandage selection, shielded melee damage and friendly-fire rules. Use Advanced when the change requires those controls instead of expecting the Basic damage cap to replace them. [1]

Choose mission door and trap conditions

Basic mission options cover trap count, the listed trap types and whether default NPC spawn points are enabled. Advanced adds expanded trap-count selection and maximum locked/open-door percentages. [1]

Set door-state percentages in Advanced when controlling the mission’s door conditions. [1]

Use the corrected settings behavior in v1.5.3

Version 1.5.3 fixes changed Damage Cap and Suspect Fire Rate values not saving. If comparing an older editor setup, account for that version change rather than continuing to rely on the earlier difficulty-based fire-rate workaround. [2]

The same update makes the firing range accessible within Mission Editor Station, providing the listed station feature while preparing the custom mission. [2]