This is a charlieplexing PCB. The figure is a black cat sitting on an unicorn (on reddit). The artwork was made by inkscape and EasyEDA. A Tinkercad simulation with arduino compatible spaghetti code: https://www.tinkercad.com/things/0iIPoKPwN5V-unicat-charlieplexing

Video from the working PCB: https://youtu.be/Z9F6bd1mocM

The ordering of the LEDs are not the same in the schematic sheet and the PCB layout. However their numbering are equal.

Moreover 100 Ohm resistors at 3V are not the most suitable for different type of LEDs (in use red, yellow, green, blue at the same time). (for example: the voltage drop of blue leds is regularly over 3V.)

Charlieplexing tables

(order of leds according the schematic)

LED HIGH    LOW
-------------------
01  PB3 PB2
02  PB2 PB3
03  PB3 PB1
04  PB1 PB3
08  PB2 PB1
07  PB1 PB2
06  PB2 PB0
05  PB0 PB2
12  PB3 PB0
11  PB0 PB3
10  PB1 PB0
09  PB0 PB1

If you want to write a sketch the following should be considered. (the below is order of leds according the layout)

LED PB0 PB1 PB2 PB3
-----------------------------------
01  -   -   L   H
02  -   -   H   L
03  -   L   -   H
04  -   H   -   L
05  H   -   L   -
06  L   -   H   -
07  -   H   L   -
08  -   L   H   -
09  H   L   -   -
10  L   H   -   -
11  H   -   -   L
12  L   -   -   H