I have listened to all of Dr. Ko's free YouTube lectures on 2D game production, and they were very helpful because they explained in detail other techniques that were not in the free lectures. The best part was that in the case of the doctor's lectures, all the materials such as images were set up, so there was no major problem in practicing. I have watched other free lectures, but I have wasted a lot of time looking for missing images, but in the case of the doctor's lectures, there was never a part like that, so I remember them. I think it will be a great help if you master the techniques by repeating and mastering them. Thank you!!!