Space is lonely and dark. The feelings this can have on long trips through space can easily drive a man insane. To prevent this, crews of ships need entertainment. But because Warships aren't exactly cruise (space)ships, there are no swimming pools or football fields. There is need for entertainment that is compact. The solution is quite simple: Video games. around every 4 men together share 1 console or PC (Note: the PCs can't run Crisis), to play video games. The suggested games are mostly shooter games, like Half Life 3 or others. The video games of choice are often realistic shooters, to train the reflexes of the crew. Commanders or other bridge personal have more PCs per person, and are highly suggested to play specially developed RTS videogames, featuring realistic troops of the HDC and are basically battle simulations.
Other ways of entertainment are gyms, on bigger ships, that also keep the crew fit, or e-books.