This app was mentioned in 9 comments, with an average of 1.78 upvotes
For what it's worth, if you are running Android check out Game Recorder +
Samsung has a version specifically for the Galaxy phones, but I'm pretty sure they just licensed the app from the link above.
If you have an iPhone, sell that and get Android.
Game screen recorder and AZ recorder both allow for easy screen recording. I don't know how well they work for games, but I've used AZ before for basic recording.
on a side note recording a video of your "desktop" on android is very easy using game screen recorder, it's what i use https://play.google.com/store/apps/details?id=com.drivergenius.screenrecorder
just set it up to record desktop without using your microphone and afterwards upload to youtube or something else.
Maybe you should try Game Screen Recorder. I never tried recording audio, but you should just test out for your own personal opinion.
I like Game Screen Recorder
I have a Note 8 so it has a built in Screen Recorder in the gaming app but the other one is Game Screen Recorder
https://play.google.com/store/apps/details?id=com.drivergenius.screenrecorder