Per Wikipedia

Into the Eagle's Nest is a computer game developed by Pandora Software and released by Mindscape in 1986 for the Apple II and in 1987 for the Amiga, Amstrad CPC, Atari ST, Commodore 64, IBM PC and ZX Spectrum, and by Atari Corporation in 1988 for the Atari XEGS.

Plot
The player character is an Allied soldier whose orders are to infiltrate the top-secret Nazi fortress called the Eagle's Nest (which consists of four castles), rescue three Allied saboteurs being held there, save art treasures the Nazis have stolen, and then destroy the Nest with explosives.[1]

Gameplay
A joystick is required for control, and the player depresses the firing button to fire the machine gun, which carries enough ammunition for 99 shots. Nazis require two well-placed shots to eliminate, and Nazis sitting at a table only require one well-placed shot. The player can sustain up to 50 shots from enemy soldiers. While inside the castles, the player finds crates which may contain art objects or explosives. The player can also find ammunition dumps, first-aid kits, and goods in the castles.[1]