Acquaria by Bit Blot
Acquaria is an action-adventure, 2D sidescrolling game designed by Bit Blot (Alec Holowka and Derek Yu). The game was originally released in 2007 for PC and was later ported to Mac in 2008.
Acquaria follows Naija, a mermaid that explores the water world of Acquaria. The journey through the underwater world, she discovers her past. The player must swim, sing and fight while interacting with elements of the world. Through singing, Naijan can move objects, affect the underwater plant life and change her physical appearance. These different appearances have different abilities used for achieving various challenges.
Acquaria is set in a unique world and has various features that are rarely seen in video games today.