red led green led

trying to make a circuit:

a user will press a single button and a green led will turn on, but randomly instead of the green led turning on a red led(flashing if poss) will turn on and an alarm(buzzer etc) will make a short loud sound whilst the red led will continue flashing until reset by user.

ps nb: although i know a fair bit about electronic components and am ok with a soldering iron, this will be my first build(done many repairs but never a build of my own)

thanks in advance for any and all help

So, you need a random number generator. You can do this with a lot of logic ICs, or you can do it with a single 8 pin PIC uController chip

How do you then generate random numbers in a PIC?

Is it complicated?

basically like a russian roulette where maybe one in ten pushes of the button would change the led and BANG your history
i was thinking maybe a 4017 johnson counter might work ??