A good start, could use improvement
First off, I will say I love the basic gameplay mechanic. Games like this are typically pretty fun and twitch reaction based.
However, games like this rely on a sensation of speed. Walls don't come up very quickly, and there is no moving background. If there was a simple background quickly scrolling to the left, the game would feel like it was going much faster, while simultaneously making the game more visually interesting.
I will say the minimalist, ASCII - like art looked very nice and fit the presentation well. I know a background might seem like it would clutter up the minimalist style, but it may be a good investment to put one in and up the framerate.
This was a fairly enjoyable game that left some good room for improvement. Hope to see more games from you in the future - possibly even a sequel to this game utilizing the ideas mentioned above. Keep it up!