I really liked your game! The concept was easy to understand and the difficulty ramped up well with the speed of the multicolored columns. The "every 5 blocks your color changes" mechanic was transparent and dictated how I would play the game.
For example, if I had one point, was red, and heading towards a column with two red squares adjacent to each other, I could press "wsws" quickly to get 4 points before changing to a different color. I'm not sure if it was intended, but it's a fun mechanic as if you have 4 points moving towards a column, you can't abuse this mechanic as you'd change colors right away.
Small decisions like the one above made the game engaging and I wonder what other additions to the game could make the player think more. Perhaps individual blocks also travel left, where you'd dodge opposite colored ones but move out of your way to grab them.
Or you could add an 'L' shaped column, where the bottom of the L is two blocks of the same color. You could go for this row if you had 1 point but wouldn't be able to go for it if you had 4.
All in all, a fun game where small additions can allow the player to really think, which I really like!