Choir by animator David Li is a hyper-casual music game that utilizes a neural network to generate melody harmonization from real choral pieces. The player is presented with an eerie scene of beady, black eyes above four closed mouths, one pair of dark pink lips positioned in front of three pairs of light pink ones, against a gradient blue-gray background with a single instruction of "pull open to sing" beneath them.
The player doesn't need to win anything or perform any tasks other than complete the onscreen instruction. When the player pulls open the lips, they're presented with four open mouths that have three teeth per mouth and long narrow tongues that stick out. The first animated mouth starts to sing. The others support it like a choir. The background becomes animated with different colors and patterns. If the player pulls the dark pink mouth wide open, the voices become louder and their range changes.
The mouths continue to sing as long as the player keeps the lips from smacking together. If the player fails to keep them open, the lips make kissy-pop noises before they reseal shut.