I'm an indie developer currently working in a rhythm game. I want to imitate GD's graphic style for this project.

At first glance I thought GD graphics were just ordinary/average vector graphics, but after putting some GD's .PNG files under the magnifier this is what I found:





Pixel art! or rendered vector graphics with some sort of dithering pattern filter, I can smell some wizardy there.

What graphic tool and/or what technique should I use to create art for my game in the same GD style?

Thank you.