It is not only possible to save screenshots of achievements in games in Windows 10, but the OS also allows you to record your activities as a movie.
Which you can then show off.
In fact, this can serve both as showing off your gaming skills, but also producing guides for other gamers.
To record game movies, simple press the Windows+G keys to bring up the Game Bar.
Here, you can click the red button to start recording.
Click again to stop.
A handy little keyboard shortcut is also available to record video, that being Win+Alt+R, and Microsoft also allows you to record your mic alongside the clip by selecting the checkbox option that is available in the Game Bar.
Recordings, with or without the microphone, are again, saved in the Game DVR section in the Xbox app where you can view them.