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8 Bit Tower Defense Game Modes: Every Mode and How to Unlock It

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Story, Raids, Expedition, Challenges, Infinite, World Boss and the seasonal Hollow Night event — what each 8 Bit Tower Defense mode is for and when you can play it.

Quick answer

8 Bit Tower Defense has six ways to play — Story, Raids, Expedition, Challenges, Infinite mode and World Boss — plus a seasonal event map. Story is available immediately; World Boss unlocks after Greenfield Outpost Act 3, Challenges after World 1 Act 6, Expedition at World 2 Act 4, and Raids once you clear the final story world, Ashen Citadel.

  • Play Story first: it is open from the start, and every mode with a shown unlock requirement — World Boss, Challenges, Expedition and Raids — is measured against your story progress.
  • World Boss is the earliest side unlock — it only needs Greenfield Outpost Act 3.
  • Expedition, Challenges and Raids are gated behind mid-game and end-game progress.

Story, Raids, Expedition, Challenges and World Boss live in the Play menu, but they are not all open at once — Story is open from the start, while Raids, Expedition, Challenges and World Boss are gated behind story progress. Here is the full picture: what each mode is for, and exactly what the game asks before you can enter it.

Every mode and its unlock requirement

Data table

Mode
Story
What you do
Pick any unlocked world and act, then defend through its waves
Unlock requirement
Open from the start (World 1, Act 1)
Mode
World Boss
What you do
Face the Tide Titan
Unlock requirement
Clear Greenfield Outpost Act 3
Mode
Challenges
What you do
Rotating challenge battles
Unlock requirement
Reach World 1 Act 6
Mode
Expedition
What you do
One squad across three worlds; pick a Relic after every win
Unlock requirement
Reach World 2 Act 4
Mode
Raids
What you do
Co-op raids for up to 4 players on Rift Gate, Coral Cove and Eclipse Spire
Unlock requirement
Clear Ashen Citadel
Mode
Infinite mode
What you do
Listed as its own play format in the official description
Unlock requirement
Advertised in the official description; no lock requirement shown

The unlock requirements above are the lock text displayed on each mode's entry in the Play menu. Infinite mode appears in the official game description as a separate offering from Story, Raids and Expedition, but the description does not detail it further, so there is nothing more to promise about it here.

Story: the backbone of the game

Story mode is where every other unlock starts. It lists every world and act so you can pick your next battle. There are 6 story worlds, from Greenfield Outpost to the Hollow King's Ashen Citadel, and each world has 6 acts. Worlds unlock sequentially: clearing a world's Act 6 opens the next one — clearing Greenfield Outpost Act 6 unlocks Sakura Shrine, and the remaining worlds open the same way, act by act.

That is why the practical answer to "which mode can I play now" depends on how far your story run has reached. A new player starts in Greenfield Outpost, and every mode with a shown unlock requirement — World Boss, Challenges, Expedition and Raids — is measured against that same ladder. For act-by-act details, see the story mode guide and the worlds list.

World Boss: the earliest side unlock

World Boss is a separate entry in the Play menu, unlocked by clearing Greenfield Outpost Act 3 — just three acts into the first world. It puts you against the Tide Titan. One player's report describes the World Boss entry as opening every hour, so it may not be continuously available; the official game description does not mention this mode, so treat the hourly schedule as a player report rather than a guarantee.

Challenges: rotating battles

The official description advertises rotating challenges, and the Play menu shows a CHALLENGES entry that requires Reach World 1 Act 6 — in other words, finishing the first world's sixth act. What rotates in, and on what schedule, is not advertised, so check the entry in game to see the current challenge.

Expedition: one squad, three worlds

Expedition is a run-based format: you take one squad across three worlds, and after every win you pick a Relic, so each victory adds a choice to make before the next battle. The Play menu requires Reach World 2 Act 4 before the entry opens. The expedition guide and relics guide go deeper on how runs and Relic picks work.

Raids: co-op for up to four players

Raids are the game's dedicated co-op format, supporting up to 4 players across three named raid maps: Rift Gate, Coral Cove and Eclipse Spire. The Play menu requires Clear Ashen Citadel — the final story world — which makes Raids the last mode to open. The raids guide covers the format in detail.

Difficulty: Normal, Nightmare and Legend

Matches can be played on Normal, Nightmare or Legend difficulty, and you can switch difficulty in the play setup before starting a battle — one player switched from Normal to Nightmare right before launching a match. The difficulty levels page breaks down what each setting means.

Playing with friends

Outside of the dedicated raid format, you can also form a party and invite other people to join before playing matches together, so regular matches do not have to be solo runs. The how to play guide covers the basics of starting a match.

Seasonal event: Hollow Night

During the Halloween period, the event menu adds a seasonal Hollow Night map, Pumpkin Patch, which requires Clear World 1 on Normal to enter. It is built as a ladder of tier stages — Trick, Treat, Haunt, Dread, Nightfall and Midnight — that award Candy for wins: Tier 1 Trick pays 200 Candy per win, with a First Win x3 multiplier on top; the event also has an event shop. Because it is a seasonal event, its availability depends on the event period. See the currencies guide and how to get Candy for more.

The realistic order to unlock everything

Because each requirement builds on story progress, the practical route through 8 Bit Tower Defense's modes is the ladder below — each step opens the next mode on the list.

Priorities

  1. 1

    Play Story from the start

    Story is open immediately, and every mode with a shown unlock requirement — World Boss, Challenges, Expedition and Raids — is measured against your story progress.

  2. 2

    Clear Greenfield Outpost Act 3

    Unlocks World Boss — the earliest side unlock, where you face the Tide Titan.

  3. 3

    Reach World 1 Act 6

    Unlocks Challenges, the rotating challenge battles.

  4. 4

    Reach World 2 Act 4

    Unlocks Expedition, the one-squad run across three worlds with a Relic pick after every win.

  5. 5

    Clear Ashen Citadel

    Unlocks Raids, the co-op format for up to 4 players — the last mode to open.

  6. 6

    Jump into the seasonal event map whenever it is live

    The Hollow Night event's availability depends on the event period, so it sits outside the story ladder.

Related Guides

Story Mode Guide

Enter Story Mode, clear its acts and unlock every world from Greenfield Outpost to Ashen Citadel.

Co-op Raids Guide

See how 4-player co-op raids work and choose between the Rift Gate, Coral Cove and Eclipse Spire.

Expedition Guide

Run one squad through three worlds with a Relic pick after every Expedition win.

Challenges Mode

Find CHALLENGES in the Play menu and learn the World 1 Act 6 unlock requirement.