10. Tetris
The simple tile based puzzle game has intrigued and infuriated gamers since its initial release in June 1984 in its home country of Russia, before taking the Western world by storm only two years later. While the concept really needs no explanation, the smooth and uncomplicated game play, punctuated by increasing difficulty levels based on the speed of tiles produced, has proven that a simple concept and addictive game play will keep even the most casual gamers entertained for decades. Originally for proof, just look at the hundreds of Tetris-like mobile games available on any given app store, most are all varying takes on the very imitable concept, but the original still holds up after all these years.