If there’s one thing Yacht Club Games knows, it’s sprites.

Classic gaming consoles could only keep track of a few moving images at a time. Super Mario, the turtle he’s stomping on, the magic mushroom he collects—each of these is a single sprite. On the Nintendo Entertainment System, sprites could be a maximum of 8 by 16 pixels, and could only have four colors each (one of those being a transparency).

Even though the NES was 1983 hardware, Nintendo sold games for the platform for a decade. As time went on, programmers learned how to draw sprites that looked like vivid animated characters even within these harsh limitations.

“If you think about drawing a smiley face,” says Sean Velasco of Yacht Club Games, “you need so many pixels just to do that, just to have a smile. It’s got to be six, seven, eight pixels across. And you never have that space, ever, on the sprite for a character’s head.” The best sprite designers, he says, would “imply a face, without having to actually draw the pixels.”

As the capabilities of game consoles improved, sprite design could have become a lost art. But today, many games look to emulate the classic design sensibilities of 8-bit gaming. One of the best is Shovel Knight, a new game for Nintendo 3DS, Wii U and PC that closely matches the look and feel of a great NES game.

At Yacht Club Games, designer Velasco and artist Nick Wozniak have devoted all their energies to studying great sprite design and applying these lessons to their work. WIRED asked them to tell us about their favorite sprites of the NES era, and what makes them so well-designed.

The best sprites are a harmonious blend of artistry and usability. “If it’s going to be in a game, it needs to be a tool for the player to understand the world,” says Wozniak.

“There’s a bunch of really bad games on the NES, and they don’t conform to any of those rules, and when you play them your brain can’t even understand what’s going on,” says Velasco. “Making sure your sprites fit into the world that you’re making is extremely important. ”