Blob Opera
There's so much great stuff here:- The state machine that seems to handle all edge cases, both in things like the tutorial and also in the procedural singing- The animation, both the rigging (maybe these are bones?) and the spring physics. They blink randomly. Their eyes follow the mouse. Matching the mouths to the vowels and consonants is really well done- The overall look and feel, including shaders, shadows, 
DOF, style, UI overlays- The synthesizing of a human voice with vowels and consonants in a fairly convincing way. Choir synths for music production can run for thousands of dollars- The real time harmonizing in a seamless way.- And on top of all that, it works on all device sizes. It actually runs better on my phone than my laptop, probably due to large monitor size (the bane of any WebGL project).Fantastic