Spring RTS Engine

No luck, installation is simply aborted because key needs to be installed.

I followed your instructions for installing on ubuntu 9.04 and get the following error message, please tell me what I have to do.

W: GPG error: http://ppa.launchpad.net jaunty Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY FC66403D8670A035