Pixlr is a free image editor
Basically, You may use the Photoshop, when you make the Logo image. But, if you don't have the Photoshop license, don't worry about it. You can use Pixlr instead of Photoshop.
This article is for how to create transparent image with Pixlr
I will use our BMG logo for this example, you can download it and follow me!
Let's get started
1. Open the sample BMG logo in the Pixlr Editor.
2. Select the Wand Tool.
3. Click the outline of sample image
4. Click the Edit > Invert Selection menu to select only the logo image. Then, Edit > Copy to copy the selected image to clipboard.
5. Click the File > New Image to paste the image. Check the both checkbox in the New image dialog.
√ Create image from Clipboard
6. Paste the copied image.
7. Click File > Save to save the transparency image. Select the PNG (Transparent, full quality) format to keep the transparency.
It's just done!
Now, you can use the transparent image to our Your Mini Games.