I played a few tricks on didi...

First day...
Puzzle 0: I pulled out the USB plug of the keyboard
[He still managed to go online... so it's too simple (as expected).]

Second day...
Puzzle 1: I meddled with the "zoom" function on the Onscreen display of the monitor to make the whole screen looked small.
Puzzle 2: I deleted his online game shortcut... and asked him to put it back himself.
I did leave "stories" (hints) on the wallpaper...
[All solved when I went back to take a look... no kick, I guessed...]

Third day...
Puzzle 3: I swopped the left and right function of the mouse...
Again, I left a story (with hint) on the wallpaper...
[Again, solved...]

All along, I thought he knew I was behind all these... but I was wrong. He didn't.

On the night of the third day... I realized that on the first day, he went to tell my mum off (asked her to be more careful when she sweep the floor). *LOL*
kekek... and for the tricks I pulled on day 2 and 3, he thought the com was down with virus... Kids are forever so frank (& adorable) and this is precisely why chating with him can be very fun & enjoyable... (he never knew what it's like when a com is down with virus, only heard about it... that's why)... then I told him that those nasty people who wrote those virus would not be so nice to leave hints around... Anyway, he told me he was quite fed-up initially cos' not familiar and not sure what exactly to do...

(see... this is precisely why I decided to let him explore the com more... yup, for his own good...)

Anyway, the game shall continue when I have the time... and I think he's looking forward to it...