Hearts of Iron is easily my favourite strategy game of all time. The meta changes constantly, which means with every update new strategies become viable. The plus side is that most old strats still often apply, and even if they don't, you can roll back to previous versions to make getting achievements easier. No DLC is wasted, as each adds something extremely fun to the game. Playing a nation as strong as the USSR, or trying your hand as little Albania, (almost) every nation is fun to play. I seriously can't recommend the game enough. Even if you aren't good at games like this, it's fun just setting the AI up to act crazily and watch how it all plays out.