I'm working on TableForge[0], it's a browser based, solo or multiplayer, D&D 5e game. In TableForge, the DM is agentic with access to tools strictly following 5e rules. The DM is responsible for narration and reacting to players but your character sheet, inventory, spells are all real server resources you manage. The DM can interact with them through deterministic 5e-based tools (dice rolls, damage, sheet updates, memory). Players can play in real time or async. You can provide the DM a premise (or pick one from the library) and it'll flesh out a full campaign story arc. Either way it's a fresh story arc reacting to your actual decisions, every time.
It’s been really fun working on it and especially rewarding seeing the game bring friends together.