Oh, you absolutely MUST use the radar for the hostages. The help screens and hintbook make that clear.
There is also a look up/down mode (Pgup/Pgdn with the keyboard) to show you parts of the level just out of view. I guess it can help in some places where you kinda know where you want to go but not how to get there. Still, I managed to beat the game without using it (because I forgot about its existence).
