The Sauerbraten/Cube2 game engine has had a major update!
The water edition has many new features including very well done water reflections and refractions that make the game have a more realistic feeling.
Also the game has...
-extremely well done shadows
-great graphics
-many great premade maps
-an awsome easy to use in-game level editor
-good single player missions
-built in bots
-multiplayer that kicks major!!!
-many multiplayer modes
-multiplayer cooperative edit
-much much much more!