Big Walk Guide
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Big Walk Big Tunnel Achievement: Enter a Big Tunnel

Open the underground tunnel network through the Yellow route, then walk into one of the network’s own entrances. Opening it is not the achievement trigger.

Big Tunnel is attached to the tunnel network the Yellow route opens. The trigger is entering one of its tunnel zones, not placing the key or opening the gates.

Achievement
Big Tunnel
Official requirement
Enter a big tunnel
Verified trigger
Enter a tunnel entrance zone
Requires
Tunnel network open
Not the same as
Riding through a railway tunnel

Where are you stuck?Open Tunnels Guide

A tunnel entrance in Big Walk

Quick Answer

Finish the Yellow route so the tunnel network opens, then walk into one of the network’s entrances. Big Tunnel is awarded by entering a tunnel zone, so placing the key, opening the gates or riding a Train through a railway tunnel is not the same thing.

Getting inside is the whole requirement.

Show Me the Entry StepBig Tunnel Not Unlocking?

This is one of the gameplay achievements. See the full achievements list

Where Are You Stuck?

Pick the line that matches your run. The tunnel network and the railway are different systems, and only one of them carries this achievement.

The Tunnels are still locked

That is a progression problem, not an achievement problem. Finish the Yellow Key route so the network opens.

Open Tunnels Guide

How to Unlock Big Tunnel

Three steps. Only the last one is the achievement trigger.

  1. 1. Unlock the Tunnel Network

    If the tunnels are still locked, finish the Yellow Key route first. That is what opens the underground network.

    Open Tunnels Guide

  2. 2. Go to an open entrance

    Use any open access point of the network rather than travelling back to one particular gate.

  3. 3. Walk inside

    Move through the entrance and into the tunnel. Getting inside is what registers the Tunnel medal.

If the achievement has not appeared, walk in through another open entrance before replaying the whole Yellow route.

Show Tunnel Access PointsYellow Area Walkthrough

What Actually Triggers Big Tunnel?

Big Tunnel is attached to the tunnel network itself, not to the Yellow Key.

The achievement comes from a trigger zone sitting in the tunnel itself. The Tunnel medal is awarded when your player enters that zone, which is why opening the network and earning the achievement are separate states.

Medal
Tunnel
Attached to
The tunnel entrances
Verified game-data detail

You do not need any of this to walk into a tunnel.

Component
MedalZone
Native event
MedalZone.OnEnter / OnEnable
Trigger surface
The tunnel network’s own entrances

Big Tunnel or a Train Tunnel?

Two different tunnels share one word, and only one of them is this achievement.

Big Tunnel

The underground network the Yellow route opens. Walking into it is what awards the medal.

Railway tunnel

Part of the Train route. Riding the Train through one belongs to the railway and does not award Big Tunnel.

Open Train Guide

Which Tunnel Entrances Count?

Use an entrance that belongs to the tunnel network the Yellow route opened.

The network has four coloured access points — Red, Green, Blue and Yellow — and they are all part of the same system. Nothing in the achievement condition names one of them, so you do not have to travel to a particular colour to get it.

A cave, a hole in the ground or any other underground corner is not the same as an entrance of this network.

Show Tunnel Access Points

Big Tunnel Not Unlocking?

Work down the list. The first line that is still true is the one to fix.

1. Is it actually part of the tunnel network?

A railway tunnel, a small cave or an ordinary underground room is not an entrance of this network, and none of them carries the Tunnel medal.

2. Is the network open?

If the entrances are still locked behind the Yellow route, this is a progression problem rather than an achievement problem.

Open Tunnels Guide

3. Did you walk inside?

Stopping at the mouth, standing under the arch or opening the gate leaves you outside the zone. Keep going until you are inside the tunnel.

4. Try another open entrance

The entrance zones belong to the network rather than to one gate, so walking in through a different access point is a reasonable way to retry the entry.

5. Platform achievement delayed?

The in-game medal and the Steam or PS5 notification can update at different times. Check your platform achievement list before replaying the whole Yellow route.

What Is Not Required

These come up often, but none of them is needed.

  • Walking the whole tunnel

    You do not have to come out the other side. Getting inside is what counts.

  • Every outlet in the network

    One entrance is enough. The achievement is not a tour of the network.

  • One specific colour

    Red, Green, Blue and Yellow access points belong to the same system, and no colour is required.

  • One specific entrance

    The Yellow route unlocks the network, but the achievement does not send you back to one particular gate.

  • A set time inside

    No number of seconds is required. Walk in far enough for the tunnel zone to register you.

Big Tunnel FAQ

如何在 Big Walk 中解锁“大有乾坤”?

先通过黄色路线打开隧道网络，再走进其中一个入口。你一进到里面就会获得 Tunnel 奖章。

开启“隧道网络”就够了吗？

不够。开启网络和获得成就是两个互相独立的状态——触发奖章的是入口区域，而不是解锁本身。

我真的需要走进隧道里吗？

需要。停在洞口或一扇开着的大门前，你仍在区域之外。

火车隧道算数吗？

不算。铁路隧道属于火车路线，而“大有乾坤”来自黄色路线所开启的地下网络。 火车指南

我必须使用黄色隧道入口吗？

不用。黄色路线负责解锁这个网络，但成就并没有指定某一扇具体的门。

隧道颜色有影响吗？

不。四种颜色的接入点同属一套系统，不要求特定颜色。

我需要一路走到头吗？

不用。走到另一头并不属于成就要求——进到里面才是。

我需要去每一个隧道出口看看吗？

不用。一个入口就够了。

为什么我打开大门后“大有乾坤”没解锁？

开启网络只是前提，不是触发条件。你仍然需要走进某条隧道里面。 隧道攻略

为什么我走进去之后“大有乾坤”还是没解锁？

先确认该隧道属于这套网络而不是铁路，然后再往里走深一些，或者换一个已开放的入口试试。

Related

The Big Tunnel entry trigger and the network’s four access points last verified on 1 October 2026.

Where are you stuck?Tunnels guide