Check out Video search by game name
https://api.twitch.tv/kraken/streams?game=CS:GO
https://api.twitch.tv/kraken/streams?game=Counter%20Strike:%20Global%20Offensive
https://api.twitch.tv/kraken/videos/top?game=CS:GO
https://api.twitch.tv/kraken/videos/top?game=Counter%20Strike:%20Global%20Offensive
These will probably give you a better result.