What do you do?
The Keeper runs the world, calls for rolls, and tracks every clue while you decide what your investigator does next.
A SOLO ROLEPLAYING EXPERIENCE INSPIRED BY H. P. LOVECRAFTEnter Arkham.
Enter Arkham.
Uncover the Mythos.
A living solo horror RPG where every mystery adapts to your decisions.
No group to organise.No scenario to prepare.No rules to memorise.
Available in English and Spanish.
See how it works100credits to begin
3Keeper voices
∞possible mysteries
1persistent investigator
INSIDE A LIVING INVESTIGATION
The story leaves evidence behind.
The app generates images of your scenes and handouts, then keeps them with your notes and evidence on a case board you can return to.
The case board is the memory of the investigation: scenes, handouts and discoveries remain connected.
Follow the full investigation in English or Spanish, with the same case history and evidence.
THE PROCEDUREFrom a whisper in Arkham
From a whisper in Arkham
to a living mystery.
Your Keeper runs the world, calls for rolls, tracks every clue and remembers what happened — so you can concentrate on the only question that matters:
The Keeper remembers.
The name in the hotel register. The witness who lied. The photograph you found three sessions ago.
Arkham does not reset.
Come back tomorrow or next month. Your investigator, evidence, injuries, relationships and unresolved leads remain exactly where you left them.
ARKHAM DOES NOT RESET
The Keeper remembers.
The name in the hotel register. The witness who lied. The photograph you found three sessions ago. The companion you left behind. The door you decided not to open.
CASE STATUSInvestigation active
LAST KNOWN LOCATIONMiskatonic Valley
UNRESOLVED LEADS3 entries
INSIDE THE ARCHIVEEverything needed to
Everything needed to
lose yourself in the mystery.
A Keeper that remembers
Characters, locations, clues, consequences, and unresolved threads remain part of the investigation.
Your choices stay yours
The Keeper describes the world and calls for rolls. It never decides what your investigator does.
Cases from anywhere
Prepare an original mystery or privately process source material you already have permission to use.
Cinematic evidence
Optional portraits, scene illustrations, handouts, case notes, and a visual archive build around the story.
A story with consequences
Health, luck, sanity, possessions, companions, and the plot tracker evolve throughout the case.
Choose the voice
Select a fast, balanced, or unflinching Keeper according to the experience you want.
MEMBERSHIPOne plan.
One plan.
Every door unlocked.
Begin with 100 included credits. Subscribe when you are ready for longer investigations, premium Keeper voices, and every illustration tier.
- Persistent campaigns and investigators
- Original scenario preparation
- All Keeper and illustration tiers
- Purchased top-ups never expire
INVESTIGATOR MEMBERSHIP$12/ month
USD. Any tax that applies is shown at checkout. Cancel any time.
420credits every billing period
Start with 100 credits →No card is needed to begin. Manage or cancel the subscription from Settings.
150 credits · One-time purchase
500 credits · One-time purchase
Any tax that applies is shown at checkout. Purchased top-up credits never expire. Available after sign-in.
FIELD NOTES
Before you enter.
Do I need to know the rules?
No. The app handles the sheet and dice while the Keeper tells you when a roll matters.
Do I need to prepare a scenario?
No. Start from a short theme and the Keeper can draft an original mystery. You can also bring your own material.
Is this multiplayer?
It is designed for focused solo play: one investigator, one persistent archive, and a Keeper available whenever you are.
How do credits work?
Credits are used only when an AI model prepares or runs part of your case. You see estimated costs before expensive preparation and image actions. As a guide, the 100 free credits cover roughly 30 turns of play with a dozen illustrations alongside, and a subscription's 420 credits a month cover around 250 turns with 60 illustrations.
What rules does Midnight Mythos use?
Percentile rules adapted from a system Chaosium publishes under the ORC License — an open licence for tabletop rules that, once granted, cannot be withdrawn. Full attribution is on the licence page. Midnight Mythos is independent, and is not affiliated with or endorsed by Chaosium.
Can I play a scenario I already own?
Yes. Bring a scenario you have lawfully obtained a copy of — one you bought, one released free, one in the public domain, or one you wrote — and the app prepares it for solo play. Your upload stays private to your account: it is never shared with other players and you can delete it at any time. See the terms of use.
Some doors only open
after midnight.
Begin with 100 credits and discover where the first lead takes you.