From the Empire Wiki Game Overview:
The Empire LRP is set in a powerful Empire that is surrounded by hostile barbarians on all sides. The Empire has grown in power and size for centuries but has experienced a decline in recent decades with territories along the borders being overrun by barbarians. Around a fifth of the territory the Empire controlled at its height has been lost to a series of incursions that an Empire focused on internal politics was ill equipped to repulse.
The Empress has recently been slain, leaving the collective player base as the most powerful individuals in the Empire. Their challenge is to restore the Empire to its former glory by regaining the lands that have been lost and to secure its future.
The Empire is formed from nine culturally distinct nations. Each nation has its own culture and customs but they are politically and legally unified. Although the players are all fundamentally on the same side there is rivalry between nations, with players competing with each other to lead the Empire and achieve their own goals.
Events represent the moments when the powerful and significant members of the Empire come together to shape its future. These are times when characters can take bold actions - there will be votes in the Senate and the Synod, opportunities to practise powerful magic, chances to make your fortune and battles to be fought that will determine the outcome of the Empire's military campaigns.