The dragging operation on the right might have some delay. I'm not sure if this is due to the design or a bug. But the game is great! The tension from the left tower defense made me need to quickly drag blocks on the right side to attack. The tension from the countdown was fully displayed.
The combo of blocks on the right side would allow me to obtain a lot of colorful blocks at once for defense, which was very satisfying!
I probably felt a bit tired after about six minutes of playing. At the same time, I realized that the invading virus would eliminate the blocks on the right side. It seems that the gray ones are useless, right? Anyway, it was really great!