You will play as Snake Logan, a top-secret CIA agent sent to the most dangerous mission ever - to deal with the hundreds of monsters attacking Metro City and destroying everythig in their path. No one knows why and you are our last hope. Original, no? Well, to make things even more difficult, your plane is shot while flying over Metro City and after salvaging the destroyed plane, you find one machine gun. Time to secure the perimeter.
When you start playing you will immediately notice how similar this game is to other platforms like Commander Keen and Duke Nukem. There's something different though (besides the title screen) - you can THROW grenades and there are enemies that can jump from one place to another.
The weapon you start and play most with, is the machine gun you have from the beginning. Scattered around the levels there are a lot of power-ups you can use though - clips for automatic fire, plasma bolts (very powerful but only 20 in a clip), 2 types of grenades (very nice since they are much more powerful than normal ammo and you can throw them far ahead) and a thing called RoboPal that flies around and fires when you fire.
Around the levels you find closets that can be opened with yellow keys you can find elsewhere in the level too. Most often they hold items that give you points, but sometimes you need to find an item cruical for the completion of the level. And to complete a level you need to do one of two things - free a hostage or (if it is a boss level) - kill the boss. To free the hostage you must find him/her and turn off a beam to get to them - and to turn off the beam you need to find special "shards". Once freed the hostage dissapears in thin air, but not before giving you a key to turn off another beam that blocks the exit. If it's a boss level, killing the boss is enough to get the key. Ther are also secret levels full of cool things - but you need to find the "Secret Level Gem" in the previous level and it's usually not easy because they're hidden.
If you are used to playing Unreal Tournament or Q3 Arena you might need some time to get familiar with the graphics, but after that you'll find out that BioMenace is one very cool and addictive game.
There's an excellent hint document that comes with the game - after installing start Bm-hint.exe.