Alpha strikers
Here i'll collect my sprites in Alpha Strike format, the indicative scale is 1pixel = 3cm, the depth of colors is 32 bits, 8 bits for the alpha channel in the outline, and they are, as far as my skills go, with coherent proportions, at least for what concern the humans.
OpenGameArt.org can automatically generate a single credits file for all of the art in this collection. Please note that, while we tried our best, this file is in no way guaranteed to be accurate, and properly attributing the work you distribute with your project remains your responsibility. You'll want to load up this file in a text editor, check to make sure everything looks good (and that any special attribution instructions are followed), and then delete the notice at the top of the file, as the notice is designed to make you look very silly if you don't check over the file and remove it.