Instrumental in giving birth to the "stealth action" genre that would go on to give us Metal Gear. The most interesting mechanic here is the AI's line of sight and how the Nazi guards detect the player. On one hand it's sophisticated enough not to trigger an entire room if one guard spots you, but at the same time there are several places where the guards seem to be able to see you through walls. The other issue I have with the game is that the layout of the rooms really doesn't impact the gameplay much. There aren't as many obvious ways to just sneak past the guards, rather you just pick and choose when you'll get into a gunfight with them. Having them surrender to you is also a neat idea.