Raising the tower…
No ads in Mjolnir — just the snow, the crosswind and thirty fortresses
Play Mjolnir: The Stolen Thunder — a free Norse tower-smash puzzle in your browser
A free browser physics puzzle. Throw the rune-forged hammer, shatter every rune-seal and topple Thrym's fortresses across 30 Norse saga chapters.
Thrym the storm-giant came over the ice while Thor slept, took the hammer off his belt, and buried it eight leagues under the earth. His price for giving it back is Freyja. Freyja's answer to that is the reason the hall still needs rebuilding. Mjolnir: The Stolen Thunder begins where the poem leaves the door open — with somebody else picking up the hammer.
You are Thrud, Thor's daughter, and the striker in your hand is a rune-forged echo of the real thing: it hits hard, but it does not hit like Mjolnir, so you cannot simply break what is in front of you. You break what everything else is standing on. Thirty fortresses, four acts, and a fixed number of throws for each one.
How to play
- Read the structure first. Find the two or three cubes everything else is standing on. A tall tower with a wide base is a different problem from a wide shelf on two legs, and a bridge folds if you take out the span instead of the piers.
- Tap to throw, drag to fine-tune. A tap throws the hammer at the point you tapped. A drag pulls the sling back under your thumb with a gold arc on screen and a ring marking the first thing it will hit.
- Pick the right rune throw. Strike never runs out. Thunder Call chains lightning through whatever it lands on. Storm Split turns one throw into three. Rune Pierce ignores ward stone and passes through two blocks — and you only get a few of each.
- Shatter every seal. The counter at the top of the screen is the whole objective. Nothing else in the structure has to fall unless it is in the way.
- Spend the last throw on the collapse. Falling blocks crush what they land on and detonate rune charges, and a collapse that starts high usually finishes the chapter for free.
Materials, and what each one actually does
| Material | Strikes | Behaviour | How to use it |
|---|---|---|---|
| Rune glass | 1 hit | Brittle, and it shatters its immediate neighbours with it. | Start a collapse or open a hole for almost nothing. |
| Ash wood | 1 hit | Light, splits in a single hit, stacks very high. | The cheap structural filler of the early acts. |
| Jotun ice | 1 hit | Shatters in chains: break one and the panel goes. | Take out a whole wall with one throw, if you hit it in the middle. |
| Amber jelly | 2 hits | Swallows most of the hammer's momentum when it is hit. | Assume it stops your throw dead. Go over it, or blow it up. |
| Grey stone | 3 hits | The working material of the saga, and the reason a bad throw looks like nothing happened. | Aim at full power or do not bother. |
| Bound iron | 5 hits | Takes five hits and ignores anything thrown under full power. | The load path is usually made of it. Bring Thunder Call. |
| Rune charge | 1 hit | Explodes when it breaks and takes the structure with it. | The best throw in the game is the one that never touches the seal. |
| Ward stone | — | A thrown hammer bounces off it without doing anything at all. | Drop something on it, thunder it, blast it, or use Rune Pierce. |
The four rune throws
| Throw | What it does | Charges | Reach for it when |
|---|---|---|---|
| Strike | 3.4 damage on impact, with a small shockwave into whatever it lands on. | Unlimited | Always. It is the honest answer to most walls. |
| Thunder Call | The impact calls lightning that runs between metal and rune, and the bolts themselves shatter any seal they cross. | 1–4 per chapter | Bound iron is in the load path, or three seals sit on the same metal frame. |
| Storm Split | The hammer parts into three bolts a beat after it leaves your hand. | 1–3 per chapter | Two or three seals sit in a row and you want them all in one throw. |
| Rune Pierce | Passes through two blocks without stopping, and is the only throw that breaks ward stone head-on. | 1–4 per chapter | A ward-bound seal is exposed and there is no roof to drop on it. |
Three stars, and where the numbers come from
Par is not a designer's guess. A beam-search solver plays thousands of simulated throws against every candidate layout before a chapter ships, in the same 120-step physics the browser runs, and only layouts it could clear inside the throw budget are kept. The structure in front of you is byte-identical to the one that was solved — which is why the chapter brief can print the skalds' own line as a real number, and the third star asks you to match it with something to spare.
| How you finish | What it means | Stars |
|---|---|---|
| Out | Every seal shattered, however many throws it took of the budget. | ★ |
| One to spare | Out with exactly one throw left in the chapter's budget. | ★★ |
| The skalds' line | Out with two or more throws to spare, on the line a solver found. | ★★★ |
The saga: four acts, thirty fortresses
| Act | Chapters | Where you are | What changes |
|---|---|---|---|
| I · Ironwood Foothills | 1–8 | The outer rune-towers | Wood, glass and the first ice. Nothing is ward-bound yet. Learn the throw, and learn that a tower falls from the foot. |
| II · The Giant's Quarry | 9–16 | Where they quarried the cold | Amber jelly to eat your momentum, ward stone on the seals, bound iron in the corners, and rune charges in the load path. |
| III · Thrym's Keep | 17–24 | The rune-bound keep | Crosswind off the ice-shelf, shield stones swinging on chains across the weak point, five and six seals per wall. |
| IV · The Hall of the Bride-Price | 25–30 | Thrym's own court | Everything, plus Thrym himself standing in front of his own wall in the last three chapters. He counts as a target. |
Past chapter thirty the Ragnarok Echoes open: fortresses rebuilt from a new seed every time you enter, with another seal, another shield stone and a little more crosswind at each depth, and every seal guaranteed to sit inside the hammer's reach. Your deepest echo is kept on your own device.
Built with nothing but code
The whole game is one page: no engine, no framework, no sprite sheet and no network request after the page loads. Every cube face, every snowflake, the aurora, the ward sigils and the lightning are drawn at runtime on a canvas, and every sound — the shatter of rune glass, the ring of bound iron, the bell of a seal breaking and the drone underneath all of it — is synthesised in the Web Audio API. The physics runs at a fixed 120 steps per second, which is also what the offline solver runs, so a throw behaves the same in a browser and on a command line. It works with one thumb on a phone and with a mouse, a keyboard or both on a desktop.
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Mjolnir: Frequently asked questions
How do you play Mjolnir: The Stolen Thunder?
Tap or click anywhere and the hammer is thrown at that point, with the elevation solved for you. Drag instead and you pull the sling back by hand with a live arc showing exactly where it will land. Shatter every rune-seal in the structure, plus Thrym himself in the last three chapters, before your throws run out. Finish with two throws still in hand and the chapter is worth three stars.
What are the materials and how do they break?
Rune glass, ash wood, Jotun ice, amber jelly, grey stone, bound iron, rune charge and ward stone. Glass shatters and takes its neighbours with it, ice shatters in chains, amber jelly eats the hammer's momentum, grey stone takes three solid hits, bound iron takes five and shrugs off anything under full power, rune charge explodes when it breaks and takes the structure with it, and ward stone refuses a thrown hammer outright.
How do you break a ward stone if the hammer bounces off it?
Four ways. Drop the structure on top of it, because a falling block crushes whatever it lands on and that is the intended answer. Spend a Thunder Call, which runs along the metal and does not care what the ward thinks. Detonate a rune charge next to it. Or throw Rune Pierce, the only throw that goes through ward stone head-on.
What are the rune throws?
Strike is the plain throw and it never runs out: heavy enough to split stone in one hit. Thunder Call chains lightning through whatever it lands on. Storm Split parts the hammer into three bolts a beat after it leaves your hand. Rune Pierce punches through two blocks without slowing and breaks ward stone, and you only ever get a few of them per chapter.
Is every chapter actually solvable?
Yes, and it is measured rather than hoped for. A solver plays thousands of simulated throws against every candidate layout before a chapter ships, and only layouts it could clear inside the throw budget are kept. The line of blocks in front of you is byte-identical to the one that was solved, which is why the chapter brief can print the skalds' own par as a real number.
What happens after chapter thirty?
The binding stone breaks and Freyja walks out of Thrym's hall on her own. Ragnarok Echoes then open: fortresses rebuilt from a new seed every time you enter, with another seal, another shield stone and a little more crosswind at each depth, and your deepest echo is kept on your own device.