Vagrantsong is an upcoming (Fall 2021 release) cooperative game with "oldschool" illustrations (resembling those of Townsfolk Tussle). You are playing as a group of vagrant trainhoppers trying to escape a ghost train.
Not much is known about it at this point, but there is a very long playthrough video posted on its BGG page for anyone with the patience to watch it. The trailer video is cool though. 😎
From the designer on the BGG forums:
Vagrantsong can be played solo as long as you are comfortable with coming up with creative solutions for some of the events in some of the Scenarios that have secret information (rolling a die to decide the random secret info, for example). These types of situations are rare, but I don't want to go into too much detail to avoid ruining the fun and surprises.
Then there's the In-Between deck, which is like an Event card system between each Scenario where players secretly make decisions on which choice they'd like to make. The reason why they're chosen secretly and independently is to avoid spreading out options so all of them are chosen (to avoid min/maxing potential), and because the choices themselves are supposed to be a little more personal/introspective in theme.
Because of those events and In-Between cards that include some secret info, we decided to label it as a 2-4 player cooperative game. I suggest playing at least 2 Vagrants in a solo experience.