Involves activities that are kept in secret, concealed from the public eye and others, either because of their illegal or improper nature.
Alternate names: Covert operation, Black operation, Secret operation
The first video game about Clandestine was released in 1982.
Although criminal activities do imply clandestine nature, they can still be done in open and criminal protagonist may not necessarily be involved in any criminal activities in the actual game story.
This is also common for military or such operations that are sensitive in nature or break international laws.
Stealth games should not be included just because they're stealth games.