I like the smooth falloff, you made a very unique "look".
Sort of odd looking though, for a "retro" look you would want to use Dithering rather than an alpha with a ramp falloff.
Sort of like making a painting of "The old West" from USA pop culture, and off to the side painting in a Porche 911, and Starbucks coffee.
The 2 technologies never really existed at the same time, if you know what I mean.
Give dithering a try, it will probably take less GPU power to render it too, if you have the Alpha blending, or alpha clip available to you.
I must say that I do like the look you already have. Very well done, and very innovative.
On a side note, I like your snake sprite too.