Like a lot of people here, I am in awe of all the great, free artiwork Kenney has produced. While making my first game Candy Grab, created as part of Candy Jam, I used Kenney's images quite extensively.
I made some modified versions of those graphics for my game, and since the originals were placed in the public domain I thought it would only be fair if the modifications were as well.
This upload features:
Note that the preview file shows the images as smaller than they actually are. The actual graphics are the same size as Kenney's originals. They are all bitmaps, but there is a vector file of the alien king character included as well.
I know these modifications are basic, but they might be useful to someone, so here they are.