Start uploading a READY web build of the game (static files: index.html + assets — e.g. Vite dist/, Unity WebGL) to a Title. Returns build_id, a one-hour upload_url and asset_base. Build the game with asset_base as its base path (or a relative './'), zip the CONTENTS of the output folder so index.html is at the zip root, upload it with curl -T build.zip "<upload_url>" (a plain HTTP PUT of the file, no headers), then call finish_build_upload. Needs a shell to run the upload — a browser-only client cannot upload files. Free: only the storage it takes counts toward the publisher's quota. The build must be the GAME ITSELF, hosted here: on the Title's idosgames.com page the game may embed (iframe) only platform hosts, never another website, so a wrapper that frames the publisher's own site shows "Content unavailable" there instead of the game. Network requests (fetch/WebSocket) from the embedded game reach platform hosts plus the Title's Blockchain.IframeConnectHosts (save_blockchain; wallet-connection hosts are always refused).