This is my old, heavily modified keyboard CK3.
Shown here are all demos from version 3.15 on 8 Apr 2016.
Quick guide with timeline:
0:02 Space, 0:15 Balls, 0:34 Rain, 0:58 Fountain
1:30 Polygons with diagonals
2:07 Polyhedrons
3:45 CK logo with wave
4:23 version info and font characters
Teensy 3.1 or 3.2 (can be overclocked to 144 MHz) and
OLED 0.96" 128x64 mono display (fixed colors: top 16 pixels orange, 2 pix gap, 48 pix blue)
filled through HW SPI (4 pins) using Adafruit GFX + SSD 1306 libraries.
My website post: https://cryham.org/portfolio/2016-keyboards-ck34/
Running my Kiibohd fork, sources are GPLv3, here: https://github.com/cryham/controller/
Used an old Logitech QuickCam Pro 9000 webcam
and Open Broadcaster Software for recording.