論文アブストラクト：Live-streaming of video games is a recent phenomenon. One driving factor is the direct communication between the streamer and the audience. Currently, besides the platform-integrated options such as text chats, streamers often use external sources to let their community better articulate their opinions. In this paper we present a case study with our tool Helpstone, a live-streaming tool for the card game Hearthstone. Helpstone provides several new communication channels that allow for a better viewer-streamer interaction. We evaluated the tool within a live-streaming session with 23 viewers using Helpstone, and interviewed the streamer. The results indicate that not every implemented interactivity option is relevant. However, in general, new communication channels appear to be valuable and novel influence options are appreciated.