From the archive
Sexy Tiles: Sidescrollers
On July 16, 2009, Adam Saltsman wrote a guide for game makers who draw their own levels. It does not teach shading; it teaches the step before, organizing tiles so a player reads the room at a glance. Pixelation, a pixel art forum, has pointed artists to it.
Semi Secret is an independent publication, not the studio that made these games; this page is an unofficial account written from the public record.
Start with the grid
Most 2D games build levels from square tiles, here 16 by 16 pixels, which makes art reusable and lines up with collision. The guide's example is Metroid Fusion on the Game Boy Advance, whose hardware actually used 8 by 8 tiles flipped and combined into 16 by 16 blocks.
Block in light and dark
Paint solid floors and walls bright and plain, and backgrounds darker so they recede. Turn the screen gray: if you can still tell solid from background with three shades, the layout works.
Make the edges pop
Add a bright outline along every surface you can stand on, and darker bands in the background tiles next to it. The guide warns that many good artists skip this organizing step and go straight to details, with disastrous results.
Then the details
Pick one light source and keep the shading consistent, so a block on the ceiling is shaded like its twin on the floor. Fusion's artists also ran a dark red outline along walls and floors, because warm colors seem to come forward and cool ones to recede.
More examples
The guide also points to Flashback, Batman on the NES, Castlevania: Harmony of Dissonance and Contra 4. Its closing point is the useful one: art in a game is first about communicating, and believable surfaces come a distant second.