The pigs don't immediately read as pigs, and they're a bit hard to see. If you make the rimlight on them greyer, it'll look like red/pink compared to the green of the scene, which should make them look more like pigs.
The scene also doesn't feel very dramatic because there are so few pigs. Put pigs behind the characters, or show what it is they're defending (also in low detail, since the focus is on the three humans). I think you should also move the current pigs up, so that they're overlapping the green grass more, which will help them stand out a little more, as well as add drama to the scene since it'll make them closer to the humans.
I'd also change the characters' drop shadows to be shaped like their shadows rather than blobs. As I recall, that game has shadows shaped like the sprites, so taking a step "back" towards the most primitive type of shadow looks odd. Since the lighting here is from above, all you'd need to do is break up the shapes a little, it's not hard to make them look like cast shadows.