Really cool concept! I love that you can only move along a single line at a time. A little more thought into the context may have helped and possibly a lives system? I think the 'only one' direction fits the theme enough for you to put in lives. However, it's a fun game and the concept works really well!
Thank you for the feedback! When I was developing the game, I wanted it to have an arcade-esque difficulty and a 'one more try' feel, so that's why I didn't implement lives. As for the context, I wanted players to be able to imagine things like why the Heart Stopper is chasing them, but I do think adding a bit more context is a good idea.