Lesson 8 gave you player-authored pressure on AI. This lesson answers what the mission is actually asking for: primary and secondary goals, soft failure that still moves time forward, and checkpoints that respect your Lesson 1 fantasy (non-lethal vs lethal, alarm rules, detection tolerance).

Lesson objective

By the end of this lesson you will have:

1. A single authority (Blueprint actor or subsystem) that tracks mission state (not scattered booleans on every pickup).
2. At least one primary objective and one optional secondary that can complete or fail without instantly ending the run—unless Lesson 1 says otherwise.
3. Checkpoint logic that respawns the player (or rewinds soft state) at a designed point when they cross a volume or trigger a rest.

Step 1: Name states before Blueprints

Align with what you wrote in Lesson 1:

If any detection is supposed to fail-forward into a harder route, encode that as Setback plus a branch (new patrol density, lights on), not as instant Failed.

Step 2: Objective manager actor

Create BP_MissionDirector (or BP_ObjectiveManager) placed once per map:

• Variables: PrimaryObjectiveId (name or enum), bPrimaryComplete, SecondaryId, bSecondaryComplete, bSecondaryFailedSoftly, MissionPhase (byte/enum).
• Functions: RegisterPrimaryComplete, RegisterSecondaryComplete, ApplySetback, TriggerHardFail, TriggerMissionComplete.
• No direct UI here—that is Lesson 10—but do call custom events or dispatchers (OnObjectiveChanged, OnCheckpointActivated) the HUD will bind to later.

Pro tip: log phase transitions to the Output Log during playtests; ambiguous state bugs show up as “it felt done but nothing fired.”

Step 3: Primary goal with a clear spatial win

Pick one readable win for the slice:

• Reach an extraction volume
• Interact with a terminal for N seconds
• Acquire a key item and deliver it to a drop-off

Implementation sketch:

1. Add a Box Collision BP_PrimaryGoalVolume with OnComponentBeginOverlap → cast to player → call MissionDirector.RegisterPrimaryComplete.
2. Guard the call: only accept overlap if MissionPhase == Active and any prerequisite flags you need (door unlocked, alarm not tripped—your design).
3. On success, optionally open a exit door or fade to a win map.

Step 4: Secondary objective (optional but teachable)

Secondaries reward explorers without blocking the main arc:

• Non-lethal takedown count, read all lore tablets, steal an optional macguffin.
• Track with counters or GameplayTags on the director.
• If the player fails the secondary (alarm locks the vault), mark bSecondaryFailedSoftly and mute related VO prompts—avoid dead-end UI later.

Step 5: Checkpoints that are fair

Checkpoint = saved transform, mission snapshot, and minimal world flags.

1. Place BP_CheckpointVolume actors at natural beats (after first guard line, after gadget tutorial).
2. On overlap, call MissionDirector.SaveCheckpoint(Index) storing player location/rotation and copy of critical bools (which doors unlocked, which guards permanently alerted if you allow that).
3. On soft reset (player chooses retry, or you auto-respawn on non-hard-fail), teleport pawn and restore flags.

Common mistake: checkpoint fires during combat and saves a guaranteed death spawn—debounce with a short cooldown or require out of combat (Blackboard Engaged false).

Step 6: Fail-forward vs hard fail

• Fail-forward: raise alert tier, lock secondary, add patrol injectors, but keep primary viable.
• Hard fail: use only for lethal fantasy, time limit blow, or story mandate from Lesson 1.

Expose TriggerHardFail as a single path (alarm console, death without retry) so QA can trace why the run ended.

Step 7: Level flow sanity pass

1. Speedrun primary only—must finish under your target minute count.
2. Ignore secondary—primary must still complete.
3. Trip every checkpoint twice (forward and backward overlap).
4. Die or trigger setback once—confirm respawn does not duplicate interactables or break AI authority.

Mini challenge

1. Add one secondary that auto-fails if the player is Engaged for more than 15 seconds cumulative—teaches timers without a full scoring system.
2. Document in a one-page design note: which states allow manual checkpoint save vs auto only.

Troubleshooting

Summary

• MissionDirector is the spine—objectives and checkpoints hang off it.
• Fail-forward is a state, not an accident.
• Checkpoints save meaningful progress, not every frame.

Further reading

• AI and Behavior Trees in Unreal – tie Setback to tree branches or blackboard tiers.
• Unreal Live Coding help – if you promote MissionDirector to C++ mid-slice.

FAQ

Use GameplayTags or enums?
Enums are fine for a class project; GameplayTags scale better for DLC-sized missions.

Multiplayer later?
Replicate mission phase and checkpoint index on the server; clients only predict cosmetic feedback.

Next: Lesson 10: UI and Player Feedback adds detection meter, objective prompts, and contrast—bound to the same MissionDirector you built here. Finish Lesson 9 first: setback and complete should both show in Output Log with no duplicate objective spam.