game drawn

Under what circumstances does the computer declare the game drawn?

Here at RHP? You have to claim the draw under the regular rules of chess. When it is your move there is a "claim draw" option. In the red bar above click on help...FAQ...then the section on draws.

You don't have to claim a draw in the case of stalemate though - if your move or your opponent's move results in stalemate then as soon as you or they submit the move then it's a draw.