Semblante is a Global Game Jam entry from a team at the Catholic University of Paraná. As is typical with GGJ games, it's more of a prototype than a complete experience; just a single level.
What's notable about it is the atmospherics; darkness, an eerie soundscape, shadow enemies gliding in the depths. Periodically, there are overhead lights, and when you pass through the light, you glow for a time and can defeat enemies until the glow fades. Jumping atop them helps you not at all. Consequently, navigating the level is a combination of platforming and using the strategically placed lights to advantage.
Also, you can scream with the X key, but I don't believe this has a game effect.
Ostensibly, your character is named Jung, and you are exploring the recesses of your own mind.
You can see how a fuller treatment might be emotionally effective -- and certainly, the complexities of the human mind and its fears is a motif that lends itself to introducing additional gameplay elements over time.