Pong
A second arcade clone — two paddles, one ball, and the column-window fix that finally cracked the OLED.
Pong is the second thing I built on the XIAO ESP32-C6, and the first thing where I really understood the OLED. Flappy was a vertical game on a sideways screen; Pong made me look at the display the way it actually wants to be looked at.
The column-window fix
Every Pong frame redraws two paddles and a ball. On the SSD1315 controller, the obvious way to do that — push a full framebuffer every tick — is slow enough that you can see the ball stutter. The fix is to redraw only the columns that actually changed: a "column window" that targets a narrow vertical strip and skips the rest of the screen. The win is dramatic. Frames that took 18 ms drop to 3.
What I'd do differently
Next time I'd start with the column window from the first commit, not after I noticed the stutter. It's not an optimisation. It's how this kind of display actually wants to be used. The full-framebuffer approach is borrowed habit from working with screens that don't care.
[Repository link will be added on publish.]
