This is a version of the tabletop game Codenames that you can play with a phone and a tablet.
Simply open the board on a tablet, and scan the QR code on a phone. You'll be automatically brought to the correct key.
(If your phone can't scan QR codes, just copy and paste the code provided into the key.)
For instructions on how the game works, read this section of the Wikipedia article.
I am not associated with Vlaada Chvátil or Czech Games in any way. This is simply a passion project of a bored developer.