Mythos Slayer has forty bosses in it, and they are all drawn by someone who is not me, because I commissioned them.
I want to be clear about the financial logic there, since there is not any. This is a free browser game made by one person. It had, at the point I placed that order, earned exactly nothing, and it has continued to earn exactly nothing since. I paid an artist anyway.
Why the bosses are Cthulhu Mythos creatures
An idle clicker is, mechanically, a spreadsheet with a progress bar. The numbers go up. That is genuinely enough to keep people playing, which is a slightly unnerving fact about all of us.
But the thing that makes you push to the next boss rather than closing the tab is wanting to see what the next one looks like. That is not a numbers problem. That is an art problem.
Cthulhu Mythos entities are perfect for this for a boring practical reason: they are already designed to be visually escalating. The rotation moves from things that are merely unpleasant up through things that should not be depicted at all. A Ratkin at boss 1 and a Hound of Tindalos at boss 28 are the same difficulty curve expressed as pictures.
They also come with names that do half the work. Night-gaunt. Gloom Wraith. You have not met the thing yet and you already have an opinion about it.
Which is why I paid for the art. The whole retention model of the game rests on the bosses being worth arriving at, and I was not going to get that out of my own drawing. The credit for those goes to @Kome_to_Matsuri and to Ankimo of the Innsmouth Project.
Clicking and summoning do different jobs
Mechanics correction, September 9, 2026: spacebar presses and taps directly damage the boss and earn gold. Recruitment is a separate purchase in the Summon panel. There are 24 recruitable unit types; each is recruited once and then upgraded. The Farmer and Villager produce gold, while the other units attack.
The basic Swordsman deals 2 damage per attack; the Demon God starts at 50 million. Unit levels and attack-speed upgrades change those rates. Their attacks run through the animation loop, so a hidden tab can pause or slow them. Closing the page does not award offline earnings.
Rebirth and a stalled run
Boss health grows by a factor of 2.42 within a cycle. Unit damage increases with levels, including a large multiplier every 50 levels. Rebirth unlocks after clearing Boss 10 and resets purchases while multiplying the existing permanent gold bonus. It preserves the current boss cycle.
The new factor is 1 + 0.4 times the highest boss cleared in the current cycle. Going deeper increases that factor but takes more time, so an optimal reset point cannot be inferred from the multiplier alone. See the current balance walkthrough for the exact calculations.
Three languages, no audience
The game ships in Japanese, English and Chinese. The main game provides language choices at the title screen.
Nobody asked for that. There is no Chinese-speaking player base clamouring for it, because as far as I can tell there is no player base clamouring for anything. I have received zero messages about this game since it went up.
I did it because a browser game costs nothing to open, and the only thing standing between someone anywhere in the world and playing it is whether they can read the button. Removing that seemed worth an evening.
What this actually is
If you tally it up honestly: commissioned art, three localisations, twenty balanced units, forty bosses, a prestige system rebuilt once. For a free game with no players and no revenue.
I do not have a business case for that. What I have is that I wanted the thing to exist and be good, and I was willing to pay a real artist to make it so, and none of that requires anyone to show up for it to have been worth doing.
Though if someone did show up, I would not hate it.
Mythos Slayer is free in the browser, no install and no account.