Grandpa's Farm - Inspired by Harvest Moon, Animal Crossing, and Stardew Valley, you play someone who's inherited a family farm. Draw cards to generate events, then write letters to loved ones talking about the events.
Epistolary - Generic setting, Collaborative, cooperative, built for this play format, RPG.
Reunion - A co-op game played on a postcard. You and your friends are scattered across a collection of strange islands. To reunite, you'll need to send clues to each other across the world.
Angels of the Railway Stations - We play lonely angels helping lonely travellers. Stationed in transport hubs, we write letters to each other talking about the people we meet and help.
Wonderlust - Wonderlust is a game of letter-writing between rival explorers. Both players will send a map back and forth accompanied by a token from their travels and a letter detailing their unbelievable exploits.
Light Year - This is a game about being on a mission in space, where all your friends have been scattered to remote relay stations around the galaxy. Send letters using each other as relays and hope that your messages will be received.
Callisto - RPG, we each take on “characters of note” in a fictionverse of our own choosing (or design)
En Garde! - Swashbuckling heroes in a tactical/duelling/RPG game designed for correspondence