What you actually do down there

Digging and gold

The map starts as solid rock with one lit room in it. You mark tiles to dig; imps walk over and clear them. Cleared rock becomes floor you can claim and build on, and some of it contains gold seams — which is nearly all of your income until your warriors start killing things.

That makes the first two minutes genuinely a decision rather than a formality. Dig toward gold and you can afford rooms early but your dungeon sprawls into open corridors. Dig compactly and you stay defensible but broke.

The seven rooms

Rooms are built on claimed floor and cost gold. Each one does exactly one thing, and tiles of the same room type that sit next to each other reinforce one another — a compact block beats the same number of tiles scattered around, by up to 40% once the block reaches six tiles.

Touching tiles of one type are also treated as a single chamber. Click any tile of it and the panel talks about the whole room rather than that one square: how big it is, and how many of your own creatures are standing in it at that moment — a Lair nobody sleeps in and a Training Room nobody trains in look identical from the outside. Chambers of two different types that share a wall each get a further flat bonus: a Forge next to a Barracks, a Lair next to a Hatchery, a Library next to a Training Room. Where you put things is a decision, not decoration.

Rooms upgrade twice, for gold. The second upgrade is the one that costs more than money — it is permanent and it is a fork. A Treasury becomes either a Vault (more storage) or a Coffer (more income), and every one of the seven has its own pair to choose between.

Imps, warriors, heroes

Imps dig, claim floor and carry gold. They are your economy and they are fragile.

An imp that drops below 45% health abandons its job and runs for a Lair, where it heals at 3 hp a second until it is back to 90% and then goes back to work. Without a Lair it runs to the Heart instead — safe, but there is nothing there to heal it, so it stays wounded for the rest of the run and panics again the next time it takes a hit. That is the practical reason to build a Lair beyond the imp cap.

Gold carried by an imp is not lost when the imp is killed. It falls on the floor where it died, and the next imp looking for work will go and fetch it before starting a fresh dig — which turns a dead courier into a decision about whether to send someone back down the tunnel the monsters just came out of.

Warriors are hired from the barracks — into slots that only a Training Room grants, which is why the first one costs 89 gold and 12 mana across two rooms — and fight what comes in. They rank up from kills — Recruit, then Veteran, then Elite — and those multipliers stack on top of whatever your barracks level gave them when they were hired. A veteran from a level-3 barracks is not the same unit as a veteran from a level-1 barracks.

A warrior with nothing to fight and no rally point set walks to a Training Room and trains there, earning the same rank XP a kill would. It is deliberately slow — roughly two and a quarter minutes of uninterrupted training for one promotion, against a wave every 45 to 55 seconds — so it is a use for genuinely quiet time rather than a faster route than fighting. Training also stops at Veteran. Elite has to be earned in combat, because otherwise every warrior would drift to Elite for free given a long enough lull, and "losing a veteran hurts" would stop meaning anything.

Heroes are rare. A hero earns XP and levels during a run, and has a cleave attack that no warrior gets — the point being that a hero is qualitatively different, not just a warrior with bigger numbers.

Waves, and the fifth one

Monsters arrive on a timer you can also trigger early if you would rather fight on your own schedule. They spawn on the open ring at the edge of the map and head for the Dungeon Heart along your own dug tunnels — anything alive they pass close to is a detour they will take. More archetypes rotate in as the run goes on:

• Grunts — the baseline, from the first wave.
• Stalkers — much faster, much softer, unlocked around wave three.
• Runners — fast and fragile, unlocked around wave four.
• Slingers — attack from range, unlocked around wave five.
• Brutes — twice the health, slow, unlocked around wave six.
• Sappers — armored, specialize in breaking down doors, unlocked around wave seven.
• Thieves — ignore the Dungeon Heart and raid your gold instead, unlocked around wave eight.

A boss-only Warlord archetype only ever appears in the dedicated boss slot, starting from wave ten.

Every fifth wave is a boss wave: a heavily scaled monster with an escort built the same way a normal wave would be. Wave size is capped at ten, so late waves get harder by composition rather than by throwing twenty bodies at you at once.

The wave straight after a boss is deliberately a soft one — the monsters in it hit and survive noticeably less than the curve says they should. Without that, the hardest ordinary wave so far always arrived while you were still rebuilding from the boss, so a run was usually lost one wave before anything looked wrong. The boss wave itself is scaled slightly up in return; the breather is a shaped curve, not a discount.

A run has a stated objective rather than running until you get bored: hold out until ten waves have been repelled. You pick a difficulty before you start — Easy, Normal or Hard — and it moves your starting gold and mana, the Heart's health, the gap between waves, and how tough monsters are and how hard they hit. It is the same map and the same rules either way, not a separate mode.

Payday

Every 45 seconds, each imp and each warrior draws 3 gold in wages from the treasury. If the gold is not there, nothing is taken — you keep whatever you had saved — and instead one random unit that has not ranked up yet walks out of the dungeon, an imp or a warrior, whichever the draw lands on. It is the mechanic that stops "build everything, worry later" from being a viable plan, and it is deliberately a nudge rather than a spiral: confiscating the savings as well used to make an underpaid dungeon impossible to climb out of.

A ranked-up unit never deserts, so pushing a unit past its first rank — by kills, by digging, or by parking an idle warrior in a Training Room — is also insurance against a lean payday. A garrison of veterans that cannot be paid grumbles and stays put.

Mana, spells, and your own hand

Gold is not the only resource. Mana trickles in on its own and Libraries are what make it flow at a useful rate. Mana is what the overlord personally spends — on hiring warriors and heroes out of the barracks, and on five spells you aim by clicking a tile:

• Heal (20 mana) — restores health to every wounded unit around the spot you clicked.
• Call to Arms (30 mana) — every warrior and hero rallies to that spot and holds it for 20 seconds.
• Lightning (45 mana) — direct damage to every enemy in the blast. The only spell that kills anything itself.
• Create Imp (35 mana) — a new imp, paid for in mana instead of gold. Stays armed, so you can click out several in a row.
• Freeze (30 mana) — slows every enemy around the clicked spot for a few seconds. Deals no damage, just buys time.

Each spell has its own cooldown as well as its price. Mana on its own only limits how many casts you can afford, which meant that with a full mana bar the answer to every emergency was to cast the strongest spell repeatedly; a cooldown limits when. Create Imp is the exception with no cooldown at all — it is economy, not a panic button.

You can also reach into the dungeon directly, without spending anything. Slapping one of your own units costs it 8 health and makes it dig or fight 50% faster for six seconds — never fatal, it stops at 1 health, because a unit you accidentally killed with a click would read as a broken interface rather than a trade-off. The Hand tool picks a unit up and drops it somewhere else, which is how you get a warrior across the map faster than it will walk. And a spike trap (25 gold) sits on a floor tile until the first monster steps on it, deals 40 damage and breaks. It is single-use and there is no way to get the gold back: unlike a room, a trap you tear down again refunds nothing at all, so moving one costs the full 25 a second time.

The other thing you can put on a floor tile is a wooden door (40 gold). Your own units walk through it as if it were not there; monsters cannot, and have to stop and bash through its 120 health instead. So a door is not a wall, it is a toll the attacker pays in time — and to keep it that way, the game refuses to place one anywhere it would seal off the only way through. A dungeon nothing can reach is not a defence, it is a run that never ends. Doors refund nothing either, on the same terms as the trap: relocating a chokepoint is 40 gold every time.

If you have played the original Dungeon Keeper

ImpKeep borrows the framing — you are the thing under the mountain, not a hero walking through it — but it is not a clone, and a few differences are deliberate enough to call out for anyone coming from the 1997 original.

Where it is going

The game is in active development. A campaign of sequential missions is the current direction for progression: today there is one map with one objective, and the campaign is the thing that turns a scored run into something you come back to.

Two things that used to sit in this paragraph as plans have since shipped. Touch works — one finger rotates or taps, two fingers pan and pinch to zoom — so the game is playable on a tablet rather than only claiming to run in any browser. And the leaderboard is live, ranked per difficulty — it appears on the home page once a run has been submitted and the server is reachable. The hand-made 3D models have grown too, since this section first shipped with just the Dungeon Heart and the imp: every room, every monster, the warrior and hero, the doors, the trap, the torch and rally flag all have a sculpted model now, in place of the procedural geometry that used to stand in for them. Still genuinely ahead: the campaign.

What survives a run has grown too, and it now has a page of its own: your account page lists what is stored against your player — purchases, achievements and lifetime stats, your daily-reward streak, your leaderboard placings, and the bug reports you have sent. Nothing there needs a sign-in to exist; the player behind it is an anonymous ID your browser generated.