hey
First of all, very nice work, and it's nice to see your progress

.
I can't remember if worms does this, nor do I know if your game engine would support this, but I was thinking maybe you should add background rocks?
edit
I quickly done an edit, and added some background rocks to show you what I mean.
Ohh, and if you do this, be careful not to blend the background with the foreground

. Also, when/if the foreground is destroyed in battle, then the background rocks should appear behind. Hmm, maybe you could generate a separate background layer based on the foreground? I dunno though, maybe this is something you can add later, after you have fully completed development of the game. I mean, I think it's better to get the game done, rather than spend time and energy trying to figure out how to add something that isn't essential.
cya