Metro 2033 is a first-person shooter with survival horror elements, based on the Russian book of the same name by Dmitry Glukhovsky. Most of the game takes place underground, but several times Artyom will have to venture outside, into the perpetual nuclear winter. Game progression is fairly linear, though areas may be explored more thoroughly for items and ammunition. Setpieces include a few on-rails sequences, missions that involve defending a location from an onslaught of monsters, and others. A few stages can be completed in a stealthy fashion.