Healing: one upgrade, unlimited purchases
The single most-asked mechanic is healing, and the answer is an upgrade rather than an item.
Cobalt Repair costs 1 Cobalt and restores part of the dome’s health — the flashing section of the health meter shows how much. Two details matter:
- You can buy it an unlimited number of times
- You can buy it even when the dome is at maximum health, which means cobalt can be sunk rather than wasted
Buying Cobalt Repair at least once also unlocks the Health 1 upgrade for that dome, which raises health capacity; Health 2 raises it again and requires Health 1 first. That chain is why a run can feel unwinnable at first and trivial later — the capacity itself is purchasable.
The safety net is Inventory Management (1 Water). It shows your iron, water and cobalt counts on screen, and if the health meter empties while you hold at least 1 Cobalt, it restores a small amount automatically. That is the closest thing the game has to a second life, and it is one water upgrade away.
Multiplayer: 8 players, two layers
Multiplayer arrived in the 13 April 2026 update and is not one mode but two stacked layers.
- Couch co-op: 4 players on one screen
- LAN and online: up to 8 players, cross-platform
- Couch can run alongside online, so 4 local players can fill half of an 8-player session
Online uses PlayFab server codes. The host starts a server and finds the code in the pause menu — there is no separate lobby. Joiners click join, type the code, and they are in. This single detail explains most “can’t find join code” threads: people look for a lobby screen that does not exist.
Multiplayer also shortens timed objectives. Iron Contribution gives 30 minutes solo but 24 minutes with a group, and its Challenge tier drops from 25 to 20.
Difficulty and map size
Four difficulties, and the last one is earned:
| Difficulty | Unlock |
|---|---|
| Normal | default |
| Hard | default |
| Brutal | default |
| You Asked For it | win a Brutal run |
Map size has three tiers — Small, Medium and Large — with Medium unlocked by winning on Small, and Large unlocked after that. Larger maps mean more travel time and longer resource chains, which punishes keepers with carry limits.
The three upgrade paths
The tech tree splits into three paths: HUD on one side, dome health in the middle, gameplay conveniences on the other. Costs are small, which is deliberate — these are quality-of-life unlocks that change how readable a run is.
Path 1 — information
| Upgrade | Cost | Requires | Effect |
|---|---|---|---|
| Hostile Proximity Meter | 2 Iron | — | Bar showing time left before monsters surface |
| Adaptive Wave Warner | 1 Water | Hostile Proximity Meter | Beep fires seconds before the bar empties |
| Exit Route | 1 Water | Adaptive Wave Warner | Dotted line to the dome’s shortest path when the warning sounds |
The 2-Iron first step is the best early purchase in the game. Without it you are guessing when the wave arrives; with it, mining becomes schedulable.
Path 2 — survival
| Upgrade | Cost | Requires | Effect |
|---|---|---|---|
| Health Meter | 1 Iron | — | Shows dome health |
| Cobalt Repair | 1 Cobalt | Health Meter | Restore health, repeatable, works at full health |
| Health 1 | Cobalt | Cobalt Repair bought once | Raises health capacity |
| Health 2 | Cobalt | Health 1 | Raises it again |
Health Meter at 1 Iron is nearly free, and it is a prerequisite for every survivability upgrade behind it.
Path 3 — economy
| Upgrade | Cost | Requires | Effect |
|---|---|---|---|
| Inventory Management | 1 Water | — | On-screen iron/water/cobalt counts; auto-restore when health empties if you hold cobalt |
| Cycle Counter | 1 Water | Inventory Management | Wave counter on the HUD |
Cycle Counter is not cosmetic if you play Guild Assignments: Showdown is scored on a 20-cycle limit, and counting waves from memory is how those runs fail.
Permanent upgrades and what survives a run
Beyond the in-run tree there is a set of permanent unlocks — Permanent Health Meter, Permanent Inventory, Permanent Hostile Proximity Meter, Permanent Cycle Counter, Permanent Inventory Management — plus offer-shaping unlocks such as Reroll Offers, Water Reroll, Three Gadget Offers, Three Supplement Offers, Additional Reroll Offers, Automated Weapons, Additional Battle Statistics and Center Marker.
Those are what persist between runs. What does not persist is the run itself: Dome Keeper is a per-run roguelike with no manual save slots, so the practical answer to “how do I save” is that progress is tracked by the permanent upgrade layer rather than by a save file you can reload.
The offer-shaping unlocks are the ones that quietly raise your ceiling. Three Gadget Offers and Three Supplement Offers change the choice set every shop gives you; Reroll Offers changes whether a bad shop is a dead end.
Resetting and starting clean
There is no in-game “reset progress” button documented on the wiki. If you want a fresh profile the reliable route is the platform’s own save-data controls — deleting the local save folder or using the storefront’s cloud-save management. Treat that as destructive: the permanent upgrade layer is exactly what you would be deleting.
Order to buy in
- Hostile Proximity Meter (2 Iron) — the wave timer changes every decision after it.
- Health Meter (1 Iron) — cheap, and gates all survivability.
- Inventory Management (1 Water) — on-screen resources plus the cobalt safety net.
- Adaptive Wave Warner + Exit Route (2 Water) — turns the warning into a route home.
- Cobalt Repair every time you have spare cobalt. There is no reason to sit on it.
- Cycle Counter (1 Water) — mandatory before Showdown.
- Health 1 / Health 2 once cobalt income is stable.
Related guides
- Dome Keeper Guild Assignments Guide — all 25 assignments and the badge rule
- Dome Keeper Characters Guide — the 4 keepers, including carry formulas
- Dome Keeper Gadgets Database — all 26 gadgets and their slots
- Dome Keeper Prestige Guide — score formula and the 4 variants
- Dome Keeper Achievements Guide — all 49 achievements
- Dome Keeper Hub — all guides for this game