Odd idea for a central mechanic for a solo journalling RPG. Pick a physical token which points in a particular direction: this might be a coin with the direction being which way the person is facing, a pencil, anything with one distinguishable end. It can be moved to point in the four cardinal directions: up, right, down, left (like road sign arrows, "away from you" is "up" and "toward you" is "down"). Each turn, you'll write a description of what happens to your character that turn, based on the prompt. You then turn the token one place clockwise (if it was pointing up, it's now pointing right; if it was pointing left, it's now pointing up.)
Now, use the direction to calculate an Event Number like so:
up: count the number of words in your description of the previous turn
right: count the number of consonants
down: the number of vowels
left: the number of "e"s
If the Event Number is ten or greater, add its digits together to get their sum (repeating if necessary) until it's a single digit.
Then, look at the Table of Events for that number to see what happens next. That would look something like:
1: you enter a new dungeon room!
2: you find treasure!
3: you're attacked by a monster! the next event is its HP
4: you can stop to rest and heal

etc etc. Seems weird but interesting. It's deterministic -- you can alter what comes next by carefully changing how you word your descriptions -- but this is not cheating, this represents choosing your actions carefully in the RP world!