In my opinion, it needs a different palette of colors to make it look retro (preferably beige, light brown) If that’s going to be a thumbnail in a game, the character should be in the spot light, or by any means more expressive. It cannot drain with the background. Now I don’t say that art is bad anyhow, it’s really impressive and climatic! Apart from the things above, it’s awesome!
It looks pretty good, but film grain and noise aren’t all that go into making a photo look old. For an example, take color. The color in your image is too saturated and bright to be 80s/90s (which is what I assume you’re going for judging by the fact it has color at all)
Notice the way the colors are somewhat dulled, flat almost. Also, light spots are very white and (most) dark spots are very black.
Don’t take this the wrong way, I like the way the image looks and the photoshop work is good, but it doesn’t necessarily capture the vintage look you’re striding for in my eyes.