Over 23000 tactics and checkmate exercises (in 1, 2, 3 and 4 moves) to be solved interactively. The applet include a tactics chess engine that confute player bad solutions in real time so he can recognise immediately why his move is not the best. For the registered users there is also the Glicko ELO rating system. It's also possible to play against the computer with 4 levels of difficulty, take back moves and get an hint.

Italy.
Website: http://www.ideachess.com/