Please adhere as closely as possible to the following sprite design limitations. We are not enforcing these limitations on a technical level because it would take too much additional processing power to do so, but maintaining our limitations is essential to keeping an authentic retro feel.
All the sprites on the screen at one time should share the same 4 palettes. Each palette contains 3 colors chosen from the system palette. Color #0 is always transparent.
Sprites are 8x8 regions and may be placed anywhere, even overlapping each other. (Overlapping could be used to achieve more than 3 colors on a single object.)
A single "actor" or object on the screen usually consists of more than one 8x8 sprite. The term we use for the entire set of sprites that make up a single object is a MetaSprite.
When the player is active on the screen, we reserve two of the sprite palettes to represent the player.
All remaining sprites on the screen at one time should share the other two palettes.
Number of Sprites at Once
There are a maximum of 64 8x8 sprites on the screen at one time, and there is a further maximum of 8 per scanline (sharing the same horizontal row) before sprite flickering occurs.
To give an example of this limitation, if the entire party is being depicted in follow-the-leader mode, and they are walking horizontally across the screen, they are already occupying the entire 8 sprites per scanline. Any NPC on the same line as them will mean that the sprites will begin to flicker slightly. (If the NPC only takes 2 more sprites, the flickering should be relatively minor since only one of the 5 metasprites will be omitted on each frame.)
Unlike background tiles, sprites can be flipped horizontally or vertically by the system. This means in some cases that you won't need to draw the same sprite facing both directions. Please remember never to flip a sprite that includes shading. (Our light source comes from the left side of the scene.)
How Sprites are Used
Overworld Sprite Use
Either an individual player character's sprite will be displayed, or a Horse and a Wagon sprite will be displayed to represent a party of multiple characters.
Either way, these sprites utilize two of the sprite palettes. Since cities and towns are scattered and usually no more than two appear on any given screen, each city or town may use its own fully customized sprite palette. There will be a few instances which wouldn't have been possible on an NES. If we were programming on an actual NES, we would have made the game choose to use only two of the palettes for the visible objects (preferably the ones called for the most times, or the ones closest to the player's current position), and the remaining objects would be displayed in the wrong palette. This would be considered an acceptable graceful degradation.
Town & Castle Sprite Use
In a town, if you are a member of a party, the horse and wagon sprite is displayed blocking the exit path, as well as the sprite of at least one other party member. These sprites are located here as part of Network Play conflict resolution, and we are allowing them to break the palette rule by each using their appropriate unique palettes.
Two palettes are reserved for your character.
Two palettes are reserved for NPCs.
If treasure chests are used, try to place them near one type of NPC only. (In theory, the treasure chest is reusing the other NPC palette while it is being shown.)
Dungeon Sprite Use
Dungeons normally do not contain NPCs. We show the entire party in follow-the-leader mode. Because all party members are from the same allegiance, we have minimized palette differences between sprites for each allegiance. Most parties will use 2 or 3 palettes at most, although it is possible to chose a party which uses "too many" palettes.
Treasure chests use the remaining sprite palette. All other dungeon sprites should be colored with the same palette as the treasure chest.
Battle Sprite Use
Battle mode has the most interesting use of sprites.
All player characters are depicted as sprites with their appropriate palette, which usually means 2 or 3 palettes.
The remaining sprite palette is used dynamically for animations. Black for fade-in/fade-out effects, pink, pastel green, white, etc., for hitpoint and MP values or "Miss" indicator superimposed over the scene momentarily following an attack. Custom colors for a weapon (which is only shown visibly during an attack, then disappears.)
Monsters do not utilize sprite palettes because they are drawn as background tiles.