How a computer game helps Finland's National Library
20 June 2011 Last updated at 23:36 BST
One more step, and a tiny creature will cross the bridge and get to safety.
Just one more step - but letters do not match, the fragile structure blows up and the brown mole falls into a digital abyss.
Digitalkoot may sound like a typical online game - but there is more to it than just building bridges and saving moles.
Every time players complete a level, they help with a real-life task - digitising huge archives of Finland's National Library.
The video footage has been given to the BBC by the game's developer, a Finnish start-up Microtask.