Playtesting and debugging

Prerequisites: a saved project, an enabled registered script attachment and any toolchain required by its language. Keep the runtime executable available alongside your editor installation.

Run, pause and advance

Choose Play, New Window or Standalone in the mode selector, then press Play.
Use embedded Play for editor-integrated testing; New Window opens a separate runtime view. Standalone exercises the staged export-like runtime configuration. It is not a substitute for clean-machine testing of a packaged game.
Press Pause to pause the runtime. The Frame button (Frame Advance) is enabled only while paused; use it to advance one requested step.
Press Resume to continue, then Stop to end the session.

Expected result: the toolbar shows session mode and fixed tick. Missing executables, startup failures and runtime supervision errors appear in Console. Do not promise that a physics tick is identical to a rendered frame.

Console and script debugging

Read Console entries for severity, subsystem and source diagnostics. Source-linked entries open the external editor at the indicated location when editor integration is configured. Use Console Copy to retain a report and Clear to clear displayed entries.

Use your language's logging API from a lifecycle callback. Verify scope, Script ID registration, enabled state, callback spelling and runtime dependencies before changing the engine. During Play, Programming → Reload Scripts attempts a reload and Restart Play starts a new session. Preserve a working source version; failure handling and toolchain constraints differ by adapter.

Inspect and review runtime changes

Select an entity to inspect available live telemetry in Inspector while the runtime is active.
Stop Play and read Review runtime changes when a proposal is available. It lists target properties and before/after values.
Choose Discard or Apply as one undoable edit. Applying is disabled for read-only documents; conflicts can fail validation and are reported in Console.
Save the scene if you applied changes you want to keep.

Expected result: runtime changes are never silently applied to authoring state. This review covers the supported property changes reported by the runtime, not arbitrary filesystem changes, all runtime-created entities or every script's internal variables.