First-person shooters are a popular genre of games in which the gamer sees the whole world through the eyes of his character, who uses primarily firearms in battle, with the exception of knives for stealth killings and other equipment.
Among free online games, there are also a lot of first-person shooters that tell both about confrontations in our time and about military conflicts of past years, including World War II.
Games of this genre usually have a linear plot, without an open world and crafting, but there are exceptions.