A story-driven first-person shooter
The Defiant is presented as a first-person shooter set against the World War II battlefields of China. Steam describes it with War, Historical, World War II, and Story Rich tags.
The official listing also describes dozens of firearms, including Hanyang rifles, Mauser-style pistols, and submachine guns. Detailed weapon stats, difficulty options, and mission systems should still be treated as unconfirmed.
What the trailers can tell you
The official trailer material is the best current reference for tone, environments, and the type of encounters the game is building toward. It is not a substitute for a final feature list.