Nuclear war, frivolous dumping of toxic waste,forced evolutionary virus; sometimes these things go horribly awry. These games all feature some variety of mutant life, formerly human or otherwise, and it's generally not a good idea to trust them.
Non-linear level design where the player is able to freely traverse the game world and choose where and when to visit certain areas in the game.
Pigs are pink, oinking mammals with a button nose and curly tail. They are rumored to eat a lot and be dirty. They don't fly, but they do bring home the bacon.
Point and click is an interface featured in a specific kind of adventure game, where players click on objects and characters to interact with them.