8 Bit Tower Defense Challenges Guide: Where to Find CHALLENGES and How to Unlock It

Quick answer

The CHALLENGES mode sits in the Play menu, listed alongside STORY, RAIDS, EXPEDITION and WORLD BOSS. It stays locked until you Reach World 1 Act 6, and the entry displays that exact requirement right on the button.

• Open the Play menu and look for the CHALLENGES entry between EXPEDITION and WORLD BOSS.
• The unlock requirement, Reach World 1 Act 6, is shown directly on the CHALLENGES entry.
• World 1 is Greenfield Outpost, and each story world has 6 acts, so Act 6 is that world’s final act.
• The requirement reads 'Reach', not 'Clear' — different wording from World 2’s 'Clear Greenfield Outpost Act 6 to unlock' entry.

Where to find the CHALLENGES entry

CHALLENGES is not a hidden or separately downloaded mode — it lives on the same mode-select screen you already use. Open the Play menu and you'll see it listed among the main modes: STORY, RAIDS, EXPEDITION, CHALLENGES and WORLD BOSS, with CHALLENGES sitting between EXPEDITION and WORLD BOSS.

While it's locked, the entry isn't just a greyed-out button. It tells you precisely what's missing by displaying the requirement Reach World 1 Act 6. That means you can check the menu at any time and know exactly how far you still have to go, rather than guessing at a hidden condition.

What "Reach World 1 Act 6" means

The requirement is tied to story progress. World 1 is Greenfield Outpost, and each story world has 6 acts, so Act 6 is the final act of the first world. In other words, you unlock CHALLENGES by playing through the STORY mode's opening world until you arrive at its last act.

Two details are worth noting:

• Reach, not clear. The requirement reads 'Reach', not 'Clear' — different wording from World 2’s Sakura Shrine entry, which asks you to clear Greenfield Outpost Act 6 before World 2 opens.
• You can track your progress in the same menu. The STORY entry shows your current world and act (for example, "World 1 Act 2"), and the world list shows each world’s act count, such as "Greenfield Outpost — Act 2/6". Comparing those against the CHALLENGES requirement tells you at a glance how many acts remain.

Because Act 6 is the final act of World 1, CHALLENGES unlocks relatively early — well before modes gated on later content. EXPEDITION, for instance, asks you to reach World 2 Act 4, and RAIDS is gated on clearing Ashen Citadel.

How the mode requirements compare

Every mode entry in the Play menu states its own condition, which makes CHALLENGES easy to place in the overall progression:

The wording differences matter. WORLD BOSS unlocks once you clear Act 3 of the first world, so it opens slightly earlier than CHALLENGES. RAIDS and EXPEDITION are aimed at players who have pushed well past World 1. CHALLENGES sits in between: it's available from the tail end of the first world, so you'll have it for most of your progression after the opening acts.

Getting to World 1 Act 6

Since the unlock runs through story progress, the path is straightforward: play STORY, clear the Greenfield Outpost acts in order, and keep going until you reach Act 6. There's no separate sign-up, purchase or side activity listed for CHALLENGES — the Play menu names story progress as the only requirement. For a fuller walkthrough of the story worlds and acts, see the 8 Bit Tower Defense story mode guide, and for how the other modes fit together, check the game modes overview.

Once you’ve arrived at World 1 Act 6, you’ve met the requirement the CHALLENGES entry displays ('Reach World 1 Act 6'). If you’re new to the game’s core loop of placing and upgrading defenders, the how to play guide covers the basics you’ll need on the way there.