It is quite fun and the idea of this game is highly interesting - If you are going to continue working on it and make a story through some short images , I believe it can become extremely enjoyable
Some things you could consider:
-One thing to add that I believe would help the player a bit is if they would see a red indicator or something similar to the areas where the "Death" columns are going to appear before they sprung up
-Coins or something similar to collect
-Upgrades / Skins -> in any case, something that would require you to have the "coins" like I mentioned before
-Differently colored Letters ? (just an idea xD)