Tower Defense in UEFN: Build the Wave-Survival Classic

Tower Defense (TD) is the strategy genre that turned a single idea — enemies walk a path, you stop them before they reach the end — into one of the most enduring formats in games. From Bloons to Plants vs. Zombies to countless Fortnite Creative survival maps, the loop of earning gold, placing defenses, and surviving escalating waves is endlessly replayable. This Game Modes entry breaks the wave-survival loop down and builds a compile-verified Verse device that tracks base health, pays out gold for kills, and ends the match when the base falls.

1. What it is

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Hold the Line

Tower Defense is a base-survival strategy mode. Enemies (creatures, in Fortnite) spawn in waves and travel a fixed route toward your base. Your job is to stop them — by placing turrets, building walls, or shooting them yourself — before they reach the end. Every enemy that leaks through chips away at your base health; when it hits zero, you lose.

The strategy is in the economy and placement: you earn currency for each kill, then spend it on stronger defenses, racing to out-scale the waves before they overwhelm you.

2. Type of game

3. The loop

The loop is a race between your escalating economy and the escalating horde.

Each wave you survive funds the defenses you need for the next — but the waves grow faster than your wallet, so every gold piece must be spent well.

4. Why it's fun

• Pure strategy payoff. A well-placed tower that shreds a whole wave is deeply satisfying — your planning did that, not your aim.
• The escalation tension. Watching a wave swell while you scramble for one more upgrade is a perfect pressure cooker.
• Co-op without friendly fire. Everyone defends the same base, so it's collaborative, not competitive — great for friends.
• Readable stakes. One health bar on one base. You always know exactly how close you are to losing.
• Replayable by tuning. Change the path, the wave sizes, or the economy and you have a brand-new difficulty curve.

5. Who made the great ones

Tower defense and base-survival are a long-running Creative staple:

• Bloons-style lane defenders and PvZ-inspired builds are perennial Creative favorites, recreating the genre's icons with Fortnite creatures on the path.
• Tower Defense Simulator-style maps (e.g. codes in the 8888-xxxx / 6666-xxxx range) hand each player a buildable defense grid against creature waves.
• Co-op horde defense islands like Fort Defense and Zombie Tower Defense pair the Creature Spawner with build slots for 1-4 player squads.
• Search the Tower Defense category on fortnite.gg or Fortnite Creative HQ for current top-rated codes — the genre churns constantly as creators tune their wave curves.

6. Examples / variants

• Classic single-path — one route, one base, place towers alongside it.
• Multi-lane — several paths converge on the base; you must cover them all.
• Hero defense — you are a tower: you fight on the path while AI defenses support you.
• Endless mode — no wave cap; survive as long as you can for a high score.

7. How to make it in UEFN / Verse

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Base Health

The devices you'll place

• Creature Manager (creature_manager_device) — governs the enemy creatures and fires MatchingCreatureTypeEliminatedEvent whenever a matching creature is eliminated, sending the eliminator. (Pair it with a Creature Spawner / Placer that produces the waves.)
• Trigger Device (trigger_device) — placed at the base / end of the path; fires when an enemy reaches it (the leak).
• Score / HUD — to display gold and base health.
• Player Spawn Pads + build slots (props or a Prop Manipulator) for placing defenses.

The Verse mechanic that ties it together

The spawner and triggers are device-driven; Verse owns the economy and the base health bar. The series staple returns — subscribe to an event, react — on the Creature Manager's MatchingCreatureTypeEliminatedEvent (a kill → gold) and a base trigger's TriggeredEvent (a leak → damage).

# creature_manager_device fires MatchingCreatureTypeEliminatedEvent : agent
# every time one of its creatures is killed — sending the eliminator.
EnemySpawner.MatchingCreatureTypeEliminatedEvent.Subscribe(OnEnemyKilled)
# A trigger at the base fires TriggeredEvent (?agent) when something reaches it.
BaseTrigger.TriggeredEvent.Subscribe(OnEnemyLeaked)

Shared base health is a single int (everyone defends the same base); gold is a per-player [agent]int map so each defender banks their own kills.

The full, compile-verified objective device

Drop this tower_defense_device into your project, wire the @editable creature spawner and base trigger, and it pays gold per kill, damages the shared base on a leak, and declares defeat when the base falls. It's a standalone creative_device, so it compiles on its own.

How it works, line by line

1. @editable spawner + base trigger let a designer drag the real Creature Spawner and the base Trigger onto this device — no hard-coded names.
2. OnBegin subscribes to the Creature Manager's MatchingCreatureTypeEliminatedEvent (a kill) and the base trigger's TriggeredEvent (a leak).
3. Gold : [agent]int banks each defender's kill rewards independently — the per-player economy pattern used all series long.
4. BaseHealth is a single var int because the base is shared — one health bar all players defend. set BaseHealth -= LeakDamage mutates it directly.
5. if (BaseHealth <= 0) triggers the defeat hook the moment the base is overwhelmed.

Gotchas

• The trigger at the base catches the leak. Wire a Trigger (or a Damage Volume) to the end of the enemy path so its TriggeredEvent fires when a creature gets through. TriggeredEvent sends an optional ?agent, so the handler takes ?agent (we don't need who leaked, just the breach). Set the Creature Manager to send its enemies toward it.
• Base health is shared, gold is per-player. Use a single int for the base and an [agent]int map for gold — mixing those up either pools everyone's money or gives every player their own base.
• set BaseHealth -= LeakDamage is direct, not a map-set. Because BaseHealth is a plain var int (not a map), it doesn't need the if (set ...) {} wrapper that map mutation requires.
• Tune the wave curve. The whole game is the ramp: each wave should grow faster than gold income so the player must spend wisely. Use the Creature Spawner's wave settings plus rising creature counts.

Recap

• Tower Defense is base-survival strategy: enemies walk a path, you stop them before they reach the end, earning gold to fund bigger defenses.
• The fun is pure strategic payoff, escalation tension, and a single readable base health bar.
• In UEFN the Creature Spawner drives the waves and the Trigger at the base catches leaks; Verse owns the gold economy and base health.
• The Verse pattern is the series staple: per-player [agent]int gold on a kill event, a shared var int base health decremented on a leak event, defeat when it hits zero.
• The wave/economy curve is the craft — make the horde out-scale the wallet so every gold piece matters.