Steam

DISCLAIMER: I'm not the author of this tutorial, I'm just reposting it.

Here's the url of the original post: https://www.reddit.com/r/Steam/comments/15a2nz1/how_to_change_a_game_icon_inside_steam/

TUTORIAL

1. Transform the image you want to use into an .ico file (size 32x32)

2. Go to "Program files(x86)/Steam/appcache/librarycache" and search for the game icon you want to edit.

3. Once you have found it, open it and just paste in your custom icon (I suggest making a copy of the original file in case anything happens)

4. Restart Steam.

5. Done!!