In brief:

Mode 0: Up to four independently movable backgrounds, but with some pretty serious color limitations. Mostly got used for title screens.

Mode 1: Up to three backgrounds, two with more colors. The SNES’s most-used mode.

Mode 2: Two backgrounds, with “offset per tile” on one of them that lets the system move columns of tiles vertically by arbitrary amounts. Used for certain special effects, like (along with raster-based scanline placement) the waving flag in Battlemaniacs, Super Turrican 2’s worms and rockets stages and Panel de Pon/Tetris Attack’s rising game boards. Horizontal offset per tile was also possible, but much less used due to the coarseness of the scroll.

Mode 3: Two backgrounds, one of them gets either 256 colors or, using direct color, being able to specify colors without palettes, with 8 bits of RGB value. Often used for high-color stills. Earthbound’s “THE WAR AGAINST GIYGAS!” screen uses it.

Mode 4: Has the high color first layer of Mode 3, and the offset-per-tile effect from Mode 2 for its second layer (which has fewer colors than in Mode 3). Rarely used. Puzzle Bobble uses it for gameplay, to independently shift the playfields from the rest of the gackground.

Mode 5: Two backgrounds, with 16 and 4 colors per tile respectively, but supports high resolution with 512 pixels per scanline. Can’t do transparency (but can kind of fake it with dithering). Notably, the high res menu screens in Secret of Mana use this.

Mode 6: Only one layer, hi-res like the second layer in Mode 5, but supporting offset-per-tile. Often considered completely unused, White_Pointer Gaming found out that Lufia 2: Rise of the Sinistrals does use it during the credits.

Mode 7: The famous mode that supports scaling, shearing and rotation of a single background layer, used for special effects and fancy 3D effects in games like F-Zero, Pilotwings and Super Mario Kart. Supports 256 paletted colors or direct 8-bit RGB color.

Notably though, Mode 7 can’t actually do 3D effects on its own; it has to use another feature called HDMA. It uses a raster effect to change the horizontal scale of the background on each scanline. As it turns out, the calculations to do this on each line are substantial, which is probably why so many games that use Mode 7 to a significant degree use one of the SNES’ coprocessor chips, like the DSP or SA-1, to help the processor out. The video then rounds out with a discussion of the Mosaic function used in such places as the map transitions in Super Mario World and Final Fantasy IV (II).

Elsewhere, Retro Game Mechanics Explained did a 16-part series covering the SNES’ hardware feature in considerable depth.

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