SPRITE SIZES
For technical reasons, it’s better to create sprites with sizes following the Power of Two rule.
The width and height of your sprite or texture should be: 8,16,32,64, 128, 256, 512… etc. pixels.
But if the image is 32x97 that works but is a little less memory efficient.
Note: The image doesn't need to be square format. It could be 32x128 ; 256x16 ; 256x512...
The maximum dimension should be 8192×8192 pixels, but keep in mind that the bigger the size, the bigger the memory consumption.
Note: Some guidelines for sprites sizes. In this case, the images are already pixelated in photoshop. But you could have saved smaller pictures (32 * 64 for the player for instance) and use the Sprite Zoom option to scale them in the game. . for the player or a small enemy: 64 * 128 pixels. or the same player, 32 * 64, zoomed in-game
. for a bullet: 32*32 or 64*64 pixels
. an item: 64*64 pixels
. a small enemy: 64*64 pixels
. a medium enemy: 64*128 or 128*128 pixels
. for a background element: 128*128 pixels or more
SPRITE ZOOM
If you wish to obtain a pixelated look, you can save smaller pictures and add a zoom factor to all sprites in your game.
The engine will use a special shader filter to keep the hard pixels and avoid flickering.
Sprite zoom: In Game editor / Settings /Sprite zoom, zoom all the sprites with a special filter
ANIMATION
You can animate your sprites. For more information, read the Animating sprites section.
TRANSPARENCY and BLENDING
Sprites are 2D game objects.
Most of the time, the picture is opaque and around it you’ll have transparent pixels.
A good idea is to save those images in png or tga.
Jpeg format is not a good format for transparency, as it will only export opaque pictures.
Note: if you are using Photoshop, the free superPng plug-in will give you better transparency