Used to be, there was pretty much one way to interact with a video game: You sat down and played it. Maybe you spent a while watching an older friend or sibling play, but gaming was never what you'd call a "spectator sport."

That's all changed in the last couple of years, with the advent of YouTube gaming celebrities and the booming popularity of online streaming service Twitch. Firing up a stream and watching someone else play a thousand miles away is now a perfectly legitimate way to enjoy a game. Best of all, anyone is free to participate on either side of the stream--and if you want to be the one gaming in front of a live audience, you can start doing it today, for free.

Here's how.

The client: OBS

To start broadcasting to Twitch, you'll need two things: desktop software that can record and stream footage from your computer, and a Twitch account. We'll start with the software.

Options abound for desktop streaming. You can find debates over their relative merits all across the Internet, but we recommend a broadcasting suite that's free and easy to set up, plus it integrates nicely with Twitch: Open Broadcaster Software (frequently shortened to OBS). We'll discuss the OBS client for Windows, but a Mac version is also available. 

Once you've downloaded OBS and run through the dead-simple installer, the client will launch. You'll see a mostly empty window with a bank of options at the bottom. Here, you'll set up the "scene" for your broadcast, which determines what will be shown in the Twitch stream. Remember that many gaming streams aren't just a plain screencast of the game itself! We'll show you how to set up a scene with three very common elements: the game stream, a webcam feed, and a watermark.

Source 1: The game stream

We'll start by adding the most important element to the scene: the game window. You have to have the game open first, so start it up and press alt + tab to navigate back to the OBS window. It won't matter whether the game is in full-screen or windowed mode.

Next, you'll add a new source to the list of sources available in the OBS window. Just right-click in the (initially empty) sources list and choose Add > Game Capture. This will pop open a second window with a dropdown list showing all the programs that OBS can see running on your system. Select the game you want to stream from the list. You can safely ignore the many other options available on this screen for now. Click OK.

Back at the OBS main window, you can click Preview Stream to see what your feed looks like so far. If you've opened your game in windowed mode, it should appear in the preview area of the window. If the game was full-screen, the preview will probably just be a black screen. That's OK--the game should stream normally once it's maximized.

Also note that you can stream your whole desktop instead of just a single program. This is a good option if you want to broadcast something that uses multiple programs, like a tutorial. Also, a number of games don't work with OBS's default Game Capture mode, but you can still stream them by broadcasting your whole desktop. To stream your desktop, right-click in the Sources box and choose Add > Monitor Capture.

Source 2: The webcam feed

If you want to give your feed a more personal touch, you can add a webcam stream to play alongside the gameplay. To do so, simply right-click in the Sources box, and click Add > Video Capture Device. You can mess with the settings in the window that pops up, but as long as your webcam is selected from the drop-down list at the very top, it should work all right.

Once your webcam is enabled as a source, you can choose where it will appear in the final broadcast. The default is the upper-right corner, but you can adjust this by clicking the Edit Scene button. A red border will appear around each of the individual sources in the scene. You can simply drag each source (such as the webcam) to wherever you want it in the frame, then click on the corner of the box to resize it. Most Twitch game streamers position their webcam feed in a small area in the upper-right corner of the feed.

Source 3: The watermark

To give your stream that extra veneer of professionalism, you can add a watermark--the ghostly little logo that appears in the bottom corner of most TV broadcasts. Just right-click again in the Sources box and choose Add > Image. There are few settings to mess with here: Pick an image, choose an opacity, and you're done. As with the webcam, you can use the Edit Scene button to choose where the watermark will display in the final stream.

You can preview the complete, three-source stream using the Preview Stream button. Look OK? Then we can move on to the Twitch side of things and start streaming.

The full stream

Twitch is simple to set up: Just visit the site and create a user account. Click your name in the upper-right corner, then in the drop-down menu that appears, click Dashboard.

You can preview your stream from the Dashboard, but it won't actually appear until you connect your OBS client to your Twitch account. To do this, click on the tab marked "Stream Key," then click Show Key and copy the code to your clipboard. Next, open up OBS and click Settings. In the Broadcast Settings, click the "Streaming Service" drop-down menu and select Twitch. (Note the other streaming services that OBS works with while you're in here.) Copy the streaming key to the field marked "Play Path/Stream Key (if any)."

At this point you'll notice a few warnings that OBS is not optimized for Twitch. You can manually adjust these settings in the menu, or you can just click the big Optimize button at the bottom. Now go back and preview your stream one final time. One handy trick: If your video ever seems to get out of the frame, click the Source that's off-kilter and press Ctrl + C to return it to the middle manually.

Once everything looks the way you want, click Start Streaming in OBS. You'll see the stream appear in your dashboard back at Twitch. Below the stream, you can enter a description and select the game you're playing, which makes it much easier for people to find your channel.

You may delve deeper into the settings for both Twitch and OBS, but at this point you have everything you need to run a successful broadcast. Have fun showing off on the big stage!