Sorry for the necro-reply... For those who did not notice, NEMO Patcher looks for a 256-color (8-bit color) icon that can be in 16x16 size and/or 32x32 pixels. Anyone can create their own via Photoshop, provided that it has to be indexed (either exact or Windows/Mac 256 colors). I tried all icons that are 32-bit (True Color) color icons (which are converted from PNG to ICO converter sites online), and NEMO does not recognize it. It has to be an 8-bit Color (256 colors) icon. An icon can be compiled not just in 32x32 size, but it can come along with 16x16 and 32x32. The function of the 16x16 is it is the one feasible and seen when you see the game window icon.