I've found some online games my son can play when he is sitting in front of the computer. Instead of just clicking the keyboards, he can interact with the games.
There are two games most suitable for his age of toddlers (12-18months). Both games are Elmo games.
1. Elmo Keyboard-O-Rama (this one they are learning about the alphabets and numbers)
2. Elmo, Zoe and Big Bird Peek-A-Boo
Try these games, they are fun for my boy and hopefully they will work for your kids too.
Now whenever he wants to play the Peek-A-Boo, he will put both his hands covering his face and then said "BOO!". Then he will point to my computer or laptop whichever is in the same room.