Where do I start?
Tom Clancy's EndWar is a real-time strategy/real-time tactics game, unfortunately neglected by its developers, released in 2008 and featuring a World War 3 where your decisions decide the course of the war. It involves three factions - the USA, the European Federation (A unified EU) and the Russian Federation (Which has again expanded into Eastern Europe. Including, to nobody's big surprise, Sevastopol). The interesting thing about EndWar is that it is not like other RTS or RTTs - you do not decide where each army strikes, or what to research, or even if you want to make nice with China so it invades Russia - you are a mere colonel in a special operations branch of your faction's army, and the only control you have over the world is where you
deploy. Whether you win or lose the battle as a result of said deployment changes whether your faction grows or shrinks. Other world events, such as typhoons or the U.S.S. George Bush being sunk by your nation's WMD and airstrikes are communicated through the world map's news service.
The campaign is split into two parts - a Prelude to War, in which the game explains the backstory and the game mechanics, as well as how and why World War III erupted and to give you a feel for each faction, and the Third World War itself. The AI is competent depending on difficulty level (On normal, for example, it is fairly competent, while on the hardest difficulty it is very competent), and the graphics are good for a game released in 2008.
All-in-all, I would very much recommend this game to everyone. Unfortunately, the Theatre of War servers (WW3 multiplayer) have been shut down and as a result players are restricted to games with friends or offline games. There are groups that still play EndWar matches, however I am not sure exactly of their URLs - they are, however, active on the Community Hub.