Ok so after selecting the type of display i want to use we have one problem.

8 rows + 8 columns red + 8 columns green = 24 pins i need for the controller

Adding 8 buttons brings us to 32 needed IO pins .... too much for the average ATMega i want to use.

Now what?

Enter: Shift registers for LED´s

Now we can control a whole column by a serial interface. But why 16 bit you might ask? Well, we can split the register into 8 red and 8 green. So we can control both colors per row at the same time in one go.

Also we can ditch 16 transistors. Looking at the cheapest i found at this time we effectively even save half a euro (1,04€ for 16 Transistors VS 0,56€ for 1 driver)