LED Watch

I am trying to build a watch and am currently trying to find out which board would be best, I am looking at size of the board and if it will be able to have 28 independently connected LED's and 5 buttons connected to it. One button would make all the LED's light up for 5 seconds, one would let you adjust the time using two others that would change the time up or down one unit, and the final button would switch between adjusting minutes and hours. Any advice would be appreciated.

Use a promini and multiplex the display. 7 segments, 4 digit selects, 5 buttons

16 of 20 IO used.

It takes a lot of fun out of it, but... https://www.sparkfun.com/products/11488