Yesterday I read this amazing tweet[archived]

Icewind Dale product idea: A solo, no DM, adventure where you play a character isolated in an outpost in Icewind Dale. Each day a few weird things happen and you record them in a journal. When you run Icewind Dale, your players find the journal of these events.

Someone mentioned[archived] the Wretched & Alone[archived] system reference design (SRD), which is a framework for creating "solo journaling games about struggling in the face of insurmountable odds to survive".

I decided to give it a try, but instead of using Icewind Dale I wrote a version for the Shadowfell, since that's where my players currently are. Here's my mini game for a solo adventure, which I intend to play with a custom character, while writing a journal that my players will find. It uses a deck of cards and a d6.

1. The PC starts with full health, no exhaustion. The PC doesn't have to be level 1, and level 3-5 should work best.
2. The PC is always on the move. Every day roll 1d8+1d12 for a location on the Shadowfell locations table[archived].
3. At the beginning of the day, roll a d6. This is the number of cards that will be pulled from the deck that day. Between cards you can do a short rest, and between days you can do a long rest (with some exceptions, see the King cards below).
   • If the card is a King nothing happens initially, but at night the PC cannot sleep due to nightmares and gains a level of exhaustion. If you draw more than one King in a given day, shuffle it back into the deck.
   • If the card is an Ace:
     • The Ace of Hearts represents salvation. An animal (rabbit? stag?) appears, clearly not from the Shadowfell. It seems to call the PC to follow it. The PC follows, but it disappears. When the Ace of Hearts appears, place 10 tokens on it. Every time a card is drawn, roll 1d6 and if the result is 6 you remove a token. Once all 10 tokens have been removed, draw another card. After that, the PC is able to follow the animal back to the Material Plane and escapes the Shadowfell. This is very unlikely to happen.
     • The Ace of Spades: the PC finds an ancient weapon that will help them. Choose something appropriate for the PC level.
     • The Ace of Diamonds: the PC is able to recruit an NPC to help them. Maybe they saved the NPC from some hazard, and the NPC wants to pay the debt (and might leave after helping them for one encounter, for example).
     • The Ace of Cups: the PC has a dream where someone shows them the location of a hidden item. When they wake up, they go the place and find a healing potion (level appropriate). They also loose a level of exhaustion.
   • If the card is odd: roll a random Shadowfell encounter[archived] for the corresponding PC level and go through combat.
   • If the card is even: roll a random Shadowfell encounter[archived], but the PC is able to hide and no combat happens.

Write down in the journal everything that happens: describe the locations, the encounters, the salvation animal, etc. Your players will then find the journal, and you can attribute special meaning to the encounters that happened or locations that are depicted, connecting them to your campaign.

This should be easy to adapt for other scenarios, assuming you have the encounter and location tables for them.