What kind of effect do you want? Sequential or random?
If you want sequential effect the simplest method is to use Decade counter IC 4017. The IC has 10 outputs which shift one by one when a clock signal is fed to it. Use 555 IC in astable mode (low frequency) to generate clock for 4017 . The output of 4017 can be used to drive triacs with the help of small signal transistors like BC547. The lamp loads should be connected to triacs.
For Random effect you can use a simple microcontroller. But you got to know the programming of it before using it.
Kinjal