You’ve probably seen lots of binary clocks and can tell the time, but this one is different in its design. Author tried to make clock as hard to read as possible, so no wander if you can’t tell the time without figuring out how this works.
It uses only 6 RGB LEDs to indicate time in binary format. Time is coded in colors and digits are overlapped or simply speaking color multiplexed. Clock is run by ATmega8535 microcontroller and it reads precise time tacks from DS3232 RTC chip. So take your time and try to tell the time or just enjoy the show.