Need more details, or stuff in the background, too empty. But looks nice in general!
Overall, I like the thumbnail, but I do think some improvements could be made. If you're making this for a video thumbnail, I recommend you try to make it more attractive (so people click it). Make the background more visible (lower the blur), and maybe also make the opacity on the gradient slightly lower. If the focus of the video is about the guns, make the guns more eye catching (add a stroke, add a starburst effect surrounding it, or even just add a drop shadow). With some improvements, I honestly think this thumbnail has true potential. Hope you the best when you improve on it!![]()
