Paradox Interactive reveals development of Europa Universalis IV is underway, and the grand strategy sequel is due in Q3 2013. Here is the announcement trailer, and there are previews of the game on Kotaku, Rock, Paper, Shotgun, and Strategy Informer where there are screenshots and further details. Here is a feature list from the video description::

Prepare to join a worldwide community of over half a million players and experience the drama and tension that only the grand stage of history can provide. Following on the success of the critically acclaimed "Crusader Kings II", Paradox Development Studio is ready to take you to worlds both old and new -- each yours for the taking.

Main Features:

• Make your own decisions: Nation building is completely flexible.
• Use your Monarch Power: In this new system, a leader's traits will direct the ebb and flow of gameplay.
• Experience history come to life: The great personalities of the past are on hand to support you as you make your mark on thousands of historical events.
• Turn the world into your playground: Enjoy over 300 years of gameplay in a lush topographic map in full 3D.
• Gain control of vital trade routes and make the wealth of the world flow to your coffers in the all-new trade system.
• Bring out your negotiating skills in a deeper diplomatic system.
• Go online and battle against your friends in a newall-new multiplayer gameplay that features hot-join, improved chat, a new matchmaking server and support for a standalone server.
• Create your own history and customize your game: Europa Universalis IV gives you the chance to customize and mod practically anything your heart may desire.