Black Hole Defense

In the game you must protect planets from enemies - asteroids and spaceships - and black holes which become bigger when something falls on them. To complete a level you need to save at least one planet. Main game mechanic is gravity, it makes enemies are attracted to planets and black holes and repulsed from most stations. You can find tips on first two levels. You can research new stations or upgrade old ones in the technology tree. You can left-click a station in game - veiw its parameters, us...