Download a transparent PNG, then follow the steps for your engine to keep its pixels sharp.
Unity (2D and UI)
Put the PNG in Assets. In the Inspector, set Texture Type to Sprite (2D and UI), Sprite Mode to Single, and Filter Mode to Point (no filter). Set Pixels Per Unit to match the scale of your project. If a 32-pixel tile represents one world unit, use 32 PPU for the sprites that share that scale. Set Compression to None and turn off Generate Mip Maps for these 2D sprites. Check that Max Size is at least as large as the PNG so Unity does not resize it on import. Click Apply, then drag the sprite into your scene.
Godot 4
Copy the PNG into the project and assign it to a Sprite2D node’s Texture. In the Inspector, go to CanvasItem → Texture → Filter and choose Nearest. To apply the setting across your 2D game, set the project’s Default Texture Filter to Nearest under Rendering → Textures → Canvas Textures. For sprites that are mostly shown at native size or larger, you can also leave mipmap generation off in the texture’s Import tab. If you change that setting, click Reimport.
Phaser
In preload(), load the file with this.load.image("potion", "assets/potion.png"). In create(), place it with this.add.image(32, 32, "potion"). The two 32 values are the x and y coordinates in the scene. In Phaser 3, set pixelArt: true in the game config to keep scaled textures sharp. This also enables roundPixels.
GameMaker
Create a Sprite asset and use Import in the Sprite Editor to load the PNG as one frame. Set the origin to match how the object sits in the room. Bottom Centre works well for a character whose feet should line up with the floor. In Game Options for your target platform, open Graphics and turn off Interpolate colours between pixels to keep edges sharp when the sprite is scaled.
Choosing a PNG size
Match the size to your game’s grid and the detail you need. Try 16 px for small pickups, 32 px for inventory icons or tile-sized objects, 64 px for more detailed characters, and 128 px for portraits. Check the sprite at its intended size in the scene. When enlarging pixel art, prefer whole-number scaling such as ×2 or ×4 so each source pixel covers the same number of screen pixels.