To start with the focus in alliteration games is for children to just be aware that there is something interesting about the sounds they are hearing. So if you say to a child ‘Look at the ssslithery, sssneaky sssnake sss’, they can hear there is something exciting and unusual going on with the way you are saying the words.
When this awareness grows through time, you then hope children will start to talk about the sounds they can hear, e.g. ‘s’ in that example, and be able to experiment a bit themselves, following an adult’s lead.
The next step, is making up alliterative ‘silly phrases’, such as ‘map mip mop mup’.
The final step is coming up with real alliterative words like ‘terrible tiger’.