Kerb Games has many viral games - including one for Construction Industry Training Board (CITB)

The Construction Industry Training Board game is at this link CITB Blocsmart viral (puzzle) game. It felt quite difficult to me but then I am not very experienced in playing games. 

ConstructionSkills

There might be alternative viral games I would go for before this ConstructionSkills one - see Move on Up (below); I've inserted this as it doesn't make too much noise up front!
NB all the links in this post will result in a Kerb Games sounds being heard!
RAF Global Rescue (Royal Air Force - Be Part of It)
Bat Out of Hell
Killawatt
NB Clicking on Read More >> below will bring up an embedded flash game, Move on Up, and play 2 seconds of Kerb Games sound. The sound can then be toggled on and off from the flash picture.