Yes. Mines of Idle Doomath is free to play in the browser and free to download on Android and iOS. Every upgrade, miner and cosmetic can be earned by playing. Optional paid packs shorten some cosmetic grinds, and optional rewarded videos grant in-game bonuses, but neither is required at any point in the progression.
No. The game is fully playable with no account, and your progress is stored locally on the device you are using. An account is only useful if you want your save backed up to the cloud so you can continue on another device, or if you want to post a score to the leaderboard under a display name you choose.
Yes. The core game is entirely local. Ads, cloud saves, the leaderboard and purchases are the only features that use the network, and when it is unavailable they fail quietly rather than blocking play. The web build is a static site, so once the page has loaded it works without a connection.
The game asks short addition, subtraction, multiplication and division questions, scaled to how far you have progressed. Harder equations pay more per answer. In the settings sheet you can enable or disable equation types, change how large the numbers get, and choose how numbers are written, including scientific notation once the values become very large. If you want a calmer session, disable the types you find slow.
No. There is no energy meter, no stamina and no cooldown that stops you from playing. The only timer in the game is the combo streak, and letting it lapse costs you the multiplier, never currency or progress.
Rewarded videos are the only advertising in the game, and they are always started by you. When one is available, a button offers a bonus — gems, a doubled offline reward, a top-up, or a saved combo — in exchange for watching a full-screen video. The ad plays only after you tap that button. Closing it early simply means no bonus. There are no banner ads, no interstitial ads and no ads that interrupt play.
The store sells cosmetic packs (pickaxes, outfits and cave themes) and a convenience pack. These change how the game looks or removes some small friction; they never increase how fast you progress relative to a free player, who can unlock the same content with gems earned in game. On mobile, purchases go through the app store; in the browser they go through Stripe. Payment details are handled by the store or by Stripe and never reach this game.
When a run slows down you can sink a new shaft. That resets the current run — minerals, upgrades and hired miners — and grants a permanent multiplier on all future income. Cosmetics, achievements, goals and gem upgrades are kept. Prestige is available to every player and is the main long-term progression loop.
The Save section of the menu can export your save as a text save code that you can keep or paste into the same section on another device. Creating a free account additionally keeps a cloud copy of the save up to date automatically, which is the easiest way to move between phone and browser.
Your save, local statistics and a small local crash log are stored on your device. If you create an account, the account details, a save snapshot, any leaderboard entry and any purchase entitlement are stored on the developer's server. You can erase local data from the Save section of the menu, and delete the account and its server-side data from the Account tab or by following the published account deletion instructions. The privacy policy lists every field in detail.
The game runs in a web browser on this site and as an app on Android and iOS. All three run the same game and the same save format, so a save code or cloud save moves between them.
Email minus4kelvin@gmail.com. Bug reports, feedback and account requests all reach the same inbox and are read by the developer. Including the device and the steps that led to the problem makes a bug report much faster to fix.