Creepers were actually intimidating in Alpha when the grass was, like them, that familiar vivid green, but ever since biomes were introduced, their color remained the same. They are easy to spot and therefore very easy to avoid. Chameleon Creepers mod aims to fix that by changing their colors depending on their surroundings.
Download link: Chameleon Creepers Mod for Minecraft 1.9.4/1.8.9
Read more: Minecraft 1.9.4 Mods