RLay

Aug 11, 2025: This project has been deprecated due to a lack of wide spread community use, and is no longer planned to receive any additional updates or support.

RLay (pronounced like "relay") is a tool that enables building Gymnasium environments with ~any language or software toolkit.

The main inspiration is interfacing with games built in powerful engines like Unity and Unreal. Adding a client or a server in the environment code will expose it for interaction with the standard Gymnasium API.

There are two possible paradigms -- the environment runs either as a server, or as a client.

ClientEnv has a relatively intuitive interpretation. The server maintains an instance of the environment, and calls its methods according to the MemServer calls. The user (or the RL algorithm) calls the methods of ClientEnv, which in turn calls the MemServer methods on the server.

ServerEnv works the other way around. It expects that the user creates a server which implements a policy, and the environment lives in a client which can query that policy. When the client queries the server, it sends an observation, and receives the following observation.

In summary, in ClientEnv:

• The underlying environment logic lives on the server
• The Env instance exists in the client
• The algorithmic logic is in the client

In ServerEnv:

• The underlying environment logic is in the client
• The Env instance exists on the server
• The algorithmic logic is on the server

The ServerEnv implementation is inspired by ML-Agents, but we generally recommend using ClientEnv.

Protocol

ClientBackend - ServerEnv:

• Handshake -- server sends a message, client sends a message
• Server sends a message to hand over control

TODO: finish this