A slow game (or is someone has a better name please do tell!) is a multiplayer game where you get some action points every day (or twice a day), that you spend on walking around and usually fighting monsters a la CRPG.
Played in a browser those games took like 5 minutes a day to play and were quite popular in the early 2000. Obviously people spent more time setting up groups going hunting or fulfilling some quest, often for weeks and weeks…
Have you played one of would you try one out?
Reminds me of the text-based role-playing heavy MUDs, where the players did their “pose” (a short paragraph describing what their character does) and you wait for 5 minutes while the other player(s) describe their move in return, often also adding a bit environment description. Some of the better player’s logfiles were basically prose you could almost publish. (Example: SpheresMUX)
Also, you got to like the name they came up with: it’s a MUSH (multi-user shared hullicination).