Duke Nukem: Manhattan Project is a traditional side-scrolling action game through eight episodes that consist of three levels each.
A madman named Mech Morphix has infected New York City with a radioactive substance called GLOPP which causes cockroaches, rats and alligators to transform into monsters. Additionally, the exotic dancers have been imprisoned, and it's up to Duke to save the day.
Each episode takes place in a new environment. You will start off travelling across the roofs of skyscrapers, then through the Chinatown streets, into the subway, sewer, a boat, factory, then finally; a space station. The levels are large, often with branching paths. Your goal is to find the keycard and rescue the lady in each one, optionally finding the few secret areas and 10 Nukes along the way. If you manage to collect all ten nukes, you will be rewarded with extra health and increase maximum ammunition capacity.
It's a decent sized game, clocking up at around 7 hours. The environments have enough variety between the levels which help keeps things interesting.
You obtain seven weapons as you progress through the game and these use three types of ammuntion. The list of guns are as follows: pistol, pipe bombs, shotgun, assault rifle, GLOPP gun, pulse cannon and rocket launcher. Ammunition is plentiful so you don't need to switch too much. The GLOPP gun reverses the effect of mutation, reducing the enemies back to their original form which can be stamped on to kill. The pulse cannon is a charge weapon that consumes a lot of ammunition.
Although you move horizontally, there are certain points where you can switch layers and go further towards the background. At other points, the camera may pan round as you turn corners or run in an arc.
Often, the camera seems a bit too zoomed in so you don't have much warning of oncoming enemies. I often launched pipe bombs whilst running in order to kill enemies without taking a hit. You can pan out the camera, but this can be awkward.
I found Duke Nukem to be quite an easy game, but it was a great game to play casually; just completing a couple of levels at a time. The simple mechanics worked well, and was very enjoyable in short bursts.