FIFE stands for Flexible Isometric Free Engine and is a cross platform game creation framework. It provides you with the ability to create a game using Python interfaces.

You can make just about any 2D game with FIFE but it is more geared toward a RTS or RPG in just about any view style (isometric ortop-down). For more information on FIFE's capabilities visit the Features page.

Fifechan is a C++ GUI library designed for games.
It comes with a standard set of 'widgets' and can use several different objects for displaying graphics and capturing user input.

Unknown Horizons is a 2D real-time strategy simulation with an emphasis on economy and city building. Expand your small settlement to a strong and wealthy colony, collect taxes and supply your inhabitants with valuable goods. Increase your power with a well balanced economy and with strategic trade and diplomacy.