The triangle can surpass the screen boundaries, which can get sometimes annoying. You can use Mathf.Clamp() to limit the movement easily, in case you didn't know.
Also, the squares only appear up and down, always at the same speed. It feels broken, somehow, and gets boring really fast. :/
It seems to need a lot of work, but it's a nice concept for a short game.
I also liked the font. What's its name? :)