A handy dandy guide for certain numbers relevant to GB studio development!

Tiles

8×8	The size of a background tile
8×16	The size of a sprite tile
16×16	Two sprite tiles, a metasprite
32×32	Eight sprite tiles, a metasprite
64×72	36 sprite tiles combined, the largest connected metasprite one can create

Sprites

3	Colours can be used for sprites (1 transparent)
4	Colours can be used for backgrounds and UI
5	Projectiles per scene
10	Sprite tiles can be loaded in one row (scanline) before dropping out
10	Active actors can be on screen at once
16	GBC Palettes total, 8 for background and 8 for sprites. Each palette can hold 4 colours
20	Active actors over a larger scene
38	Maximum amount of 8×16 sprite tiles on screen at once (2 reserved for Emote)
96	Max amount of sprite tiles in a scene total

Backgrounds

128	Max Background Tiles in a scene to be able to have 96 sprite tiles available
192	Max Background Tiles in a scene and still be able to use dialog/text. 64 sprite tiles available
256	Max Background Tiles in a scene that isn’t logo mode. 64 sprite tiles available
360	The amount of tiles that make up a 160×144 resolution. All tiles can be unique in logo mode. 12 sprite tiles are available

Dimensions

160 x 144	The base resolution for the Gameboy and smallest size for a scene
512 x 2040	Maximum size for a scene height wise
1016 x 1024	Maximum size for a scene equal-ish size
2040 x 512	Maximum size for a scene length wise

Colors

	071821	Darkest tone for sprites and backgrounds
	306850	Mid dark tone for backgrounds only
	86c06c	Mid light tone for sprites and backgrounds
	e0f8cf	Lightest tone for sprites and backgrounds
	65ff00	Transparency for sprites