I really like the idea of the game! For me it felt like 3 friends had been abducted by aliens and are on an alien planet and now the alien also somehow chases them trough the terrain :D
It would certainly improve the feeling of being chased if the camera would show who is chasing the player character. Furthermore, maybe a "goal" of some sort (like: "Survive for 30 seconds in this terrain") could help define the game itself better.
But overall - good job for a game made in a week and good job if this is your first one! :) keep going!