The room also needs to be a Faraday cage, in case a player has a radio device implanted under the skin, or swallowed one. Don't forget soundproofing to prevent

The room also needs to be a Faraday cage, in case a player has a radio device implanted under the skin, or swallowed one. Don't forget soundproofing to prevent communication via noises. Oh, and enough earthquake proofing to prevent communication via vibrations.