Shamus

Description
Infiltrate the lair of the elusive Shadow, shoot and sneak your way through his army of robotic minions, and hunt him down before he does the same to you. Starring in the titular role of Shamus, you will have to find your way through over 120 rooms in this cross between Berzerk's "robots in a maze" action and Adventure's exploration of a predefined game world.
The elusive villain's henchmen will express their disapproval of your plans in rather strong terms, namely with showers of bullets. What's more, once they're dead they don't necessarily stay that way: each time a room is re-entered, a random selection of them will respawn. The Shadow has also arranged for electrified walls throughout his compound, so bumping into them will prove quite lethal.
The labyrinth of chambers is divided into four levels, with multiple locked doors that'll have you wandering around in search of the right keys. If you tarry too long in the same room, a bulletproof Shadow (taking a page from Evil Otto's book) will drop by to discourage loitering.
The C64 port features a slightly altered map and has four bonus maps and the enemies stay at the same speed where as in the original they would get faster as the levels increased. The VIC-20 version has many redesigned due the walls being drawn larger than in the other versions, It has also been reduced to only having 32 screens. The much later released Game Boy Color version adds in story cutscenes and the four levels now each feature a distinct theme. The camera view is also now zoomed in so only a portion of a room can be seen at once.