If your game, try making the liquid object transparent with a slightly darkened color. Also your base material doesn't seem to be catching any shadows,(are shadows off?) maybe the ambience is set high.....(clued in by the light hitting the green at the top) If it's a transparent green, you can put a darker non-transparent plane underneath it.

Try different set-ups....I like the concept of the liquid.

___
Ockham's razor- It's that simple