It's a textual adventure (some graphic embellish it, but is purely decorative and has no role in the game).
You give commands usually composed by a verb plus a noun (e.g. "go north", "examine desk", "drink potion") and are told what happens ("you cannot go in that direction", "there is a pen on the desk", "you feel reinvigorated"). You have to explore the locations, collect items, use them when appropriate and in general imagine how to overcome the various problems in order to accomplish the final goal of the adventure.
You are Frank Russel, the only survivor in your village after its bombardment by the enemy forces. After a brief telephonic contact with the allied forces, you are going to infiltrate a nearby enemy camp to steal their plans and find a radio to communicate again with your allies.