It would depend on the publisher's intent. If you create a game, movie, or book using my assets, you can sell that game, movie, or book without restrictions. You can even sell the game to a publisher. However, you cannot redistribute the assets themselves. A good question to ask is: Does my project compete with the assets in any way? If you use the assets in a Gamemaker project, you cannot sell the project file, but you can sell the game exported from that project file. I hope that makes sense. Let me know if you have any other questions.