🔧 XDC Underground — Ownership, Persistence & Claiming

Tunnel bases don't use flags or territories. This guide explains what replaces them, who is allowed to take your base apart, and how to protect yourself with a screwdriver.

No flags underground

You cannot build a flag or claim a territory inside a tunnel system, in the way you would above ground. You don't need to, though — and there's a good reason we've done it this way. If tunnels used the vanilla flag system or our territory system, the flag would effectively act as a radar that could be used to detect nearby tunnel systems. Keeping flags out keeps bases hidden.

(Surface flags are unaffected — a flag on the ground above a tunnel works as normal. Note that you can't dig an entrance inside someone's territory.)

Persistence: the core is your flag

The persistence job a flag normally does is taken over by each core structure. As long as a core exists, it refreshes the lifespan of every object in its cube every 5 days — the same interval a flag uses. Every cube in the system does this, including ones that have collapsed (so gear buried in a cave-in is kept until you dig it out), plus the area around the hatch on the surface.

A few consequences:

• As with a flag, the refresh only fires every 5 days, so it only helps items whose lifespan is already longer than that — storage, base structures and the like. Short-lived junk still rots away between refreshes.
• The refresh is tied to real time, so restarts don't reset it.
• If a core is destroyed, its cube stops refreshing. Keep cores standing (see the Stability guide) or your storage will eventually despawn.

This is a brand-new system — please let us know if you notice anything not persisting as it should.

Who owns a tunnel system

Whoever builds the entrance hatch is automatically set as the owner of the first cube (the one under the hatch — the origin). The only people who can dismantle walls or remove vault doors in a claimed cube are that owner and members of their group (using the XDC Groups mod — see the Groups guide). Cores can't be dismantled at all; they can only be destroyed by raiding or collapse.

The crucial catch: only the first cube is owned automatically. Every cube you dig after that starts unclaimed. In an unclaimed cube anyone can dismantle walls — including someone who has tunnelled in from outside.

That's why we've added a way to claim your cubes. You don't have to claim your tunnels — it's an added protection — but if you don't, an intruder who reaches an unclaimed cube can take its walls apart in seconds and walk off with the refund.

Claiming a cube

Take a screwdriver in your hands, stand inside the cube you want to claim, and aim at the floor or any part of the core. The prompt tells you the cube's status; if it's claimable it reads Claim Cell. Hold the action to claim it.

• You can claim a cube if you, or a member of your group, already own a cube directly next to it. You claim outward from what you already hold, one cube at a time. Claiming a fresh cube takes about 5 seconds.
• The screwdriver is ruined when the claim succeeds. Bring a stack of them. A refused attempt costs nothing.
• Claiming is noisy — anyone within about 60 m hears the wrench.

The screwdriver cost is the whole point: if an enemy tunnels into your base, they have to have prepared well — a screwdriver per cube, and a long, noisy takeover of each one — before they can dismantle your whole tunnel system.

Taking over someone else's cube

You can also claim a cube that another team owns, but only if you or your group already own a cube next to it (your own tunnel counts, even if it's a different tunnel system). A hostile takeover takes a full 60 seconds, during which you're locked in place and audible — it's slow and risky under fire, deliberately. Once it completes the cube is yours and you can dismantle it like any of your own.

Within your own group, a cube owned by a group-mate can only be taken over by someone of a higher group rank (Officer over Member, Owner over Officer). You can't take a cube from your own owner.

Starting from nothing: the origin rule

What if you want to take over a tunnel system you hold nothing in — an abandoned base you've found, say, or one you've raided? You can't just claim any cube; adjacency needs something to be adjacent to. The rule is:

• The first cube you claim in a system where you own nothing must be the origin cube (the one under the hatch), and
• you must be the owner of the codelock on that hatch — meaning you've fitted your own codelock and set the code on it. Knowing someone else's code doesn't count, and a lock with no code set doesn't count.

So to take over a found base: get in, put your own codelock on the hatch and set a code, then claim the origin cube with a screwdriver. From there you expand outward by adjacency like anyone else. If the hatch already has someone's lock on it, that lock has to be dealt with first — a codelock can only be removed by its owner (or by anyone, if its owner never got round to setting a code).

Reading a cube

While you aim at a core with a screwdriver, the prompt line is a live readout:

• "This cell is yours." — you own it.

• "Your group's: [name]" — a group-mate owns it.
• "Claim Cell" / "Claim Cell - take over" — you can claim it now.
• "Claim a cell next to one you already own first." — unclaimed, but you hold nothing adjacent.

• "Claimed - you can't claim this." — another team owns it and you can't take it. No name, no ID — the readout never reveals who owns an enemy base, so it can't be used to snoop.

What ownership does and doesn't do

Ownership is about dismantling. It does not:

• stop anyone walking through your tunnels (use vault doors and codelocks for that),
• stop anyone building walls in your cubes,
• stop anyone raiding you with explosives or bullets.

Raiders don't need to claim anything to blow their way through; claiming only stops them taking the cheap route and dismantling. Claims survive restarts and core upgrades, and you can claim during a raid.

Quick tips

• Claim every cube as you dig it. It's 5 seconds and a screwdriver.
• Keep screwdrivers in the base — they're consumed on every successful claim.
• Set a code on your hatch lock straight away; the codelock owner is the only person who can ever start a takeover from the hatch.
• Check the readout occasionally — if a cube of yours reads as someone else's, you've been tunnelled into.