"The second game in the Commander Keen series.
Keen returns to Earth only to find the Vorticon mothership hovering above with its deadly X-14 Tantalus Ray cannons locked on to eight of Earth's greatest landmarks: the Big Ben (London), the Sphinx (Cairo), the Sydney Opera House (Sydney), the Statue of Liberty (New York), the Eiffel Tower (Paris), the Colosseum (Rome), St Basil's Cathedral (Moscow), and the White House (Washington D.C.). Keen has to find and deactivate each of the cannons to save Earth. Unlike the first game which had a happy and friendly atmosphere, almost everything in this game is hostile towards Keen, from the floating machine gun robots to the electrified floors. The engine has more features than the first episode, such as light switches and moving platforms."
Source: Wikipedia, "Commander_Keen," available under the CC-BY-SA License.