When you are creating unique Seven Co-op game icons, you should do:
Use bold colors and simple shapes
Make them recognizable
Incorporate elements from the game’s theme for cohesion
Use tools like Photoshop or GIMP
Also, for banners, follow a similar approach, and ensure your icons and banners match the overall style of Sven Co-op game icon banners.
Source - https://sportsbyte.net/sven-coop-game-icons-banners/