This is the sprite sheet, or “atlas”, of Frank, the hero of The Incident. Here’s my Photoshop setup:
The ‘Nonsaveables’ layer group contains the background (with a repeating grid pattern) and labels identifying the frames. I turn this group off when saving the final PNG.
The game contains dozens of these atlases. The biggest one includes all the falling items in one ginormous grid. There’s also an XML file which defines their positions, polygons, names, materials, etc.