There are a handle of quality of life changes that would go a long way to making this play more smoothly. Namely:
- A clear way to remove blocks from the queue (is this even possible currently?)
- A faster way to add some blocks onto the queue (clicking, probably, since it seems like you can't place them arbitrarily anyway)
- Some indication of the order things will execute in, and what symbols do what
What you've got here is a solid seed of an idea, with some deeper mechanics, you could design some really cool levels.