The following is my general understanding of such licensing issues, IANAL.
GPL/LGPL, Apache, MIT, those are all software licenses, they have nothing to do with art assets you may use in your game.
GPL: This is the license that started the open source movement. If you use a piece of GPL code, your entire project (the code, not the art) has to be released under the GPL. GPL is strictly a non-commercial license, so no using GPL code in something you plan on selling.
LGPL: The more permissive cousin to the GPL. The LGPL is more permissive than the GPL. You can use LGPL code in a commercial program, but it has to be used as a dynamically linked library (DLL), You can not compile it into your main program, and if you’ve made any changes to the actual LGPL code, you have to release those changes under the LGPL.
Now, there is a difference between the code that runs your game, and the art assets that make up the visuals of our game, and the story of your game.
If you use GPL code to make your game, you do have to release the entire code base for your game under the GPL, but you do not have to license your art, music, or story/dialogue under the GPL.
The most common open license that applies to both code and art is the Creative Commons license.
Creative Commons is a lot easier for people to understand. There are variations of it.
Here are the various ways things are released under the Creative Commons License:
CC0 - Public Domain You can do anything you want with it except claim you created it or put it under a different license.
CC-BY - Attibution. Same as above, but you have to give credit to the creator.
CC-BY-SA - Same as above, but you must share any changes you make to it.
CC-BY-NC - You must give credit to the creator, and can not use it in a commercial product.
CC-BY-ND - You must give credit to the creator, and can not modify it.
CC-BY-NC-SA - You must give credit to the creator, and can not use it in a commercial product, and you must share any changes you make to it.
CC-BY-NC-ND -You must give credit to the creator, and can not use it in a commercial project or make any changes to it.
The great thing about the Creative Commons licenses, as opposed to the GPL, is they only target the actual asset or code thats licensed under them.
Say you use a C# class to add a leader board to your game, an its licensed CC-BY-NC-SA.
You have to include an attribution to the codes author, you cant use it in a commercial project, and you have to share any changes you make to it, but you dont have to release the entire codebase of your game under that license.