Searching for Game
If you are saying you are playing “Alien: Isolation” and your stream doesn’t show under the game category then go on your Twitch Dashboard and make sure the game you are playing is set up from the list of games Twitch provides.
Searching for Stream Title
If you are saying that your stream title is “Alien: Isolation” and when you search it on Twitch it doesn’t come up then this is nothing new, not every stream is shown when searching for the stream title.