"BUTTS: The VR Experience"

"BUTTS: The VR Experience" is an animated VR short film about love, trust, and learning what it means to be truly free. With an Android phone and Google Cardboard, one can transport oneself into a brand new bright and colorful world of happiness and excitement, and even make some friends along the way. "BUTTS: The VR Experience" will make you laugh, cry, fill you with unimaginable bliss, and return you to that innocent place of child like wonder you've long forgotten.

It's one of those real-time 3D graphics engines so you probably need a pretty decent phone to run it.