"Use the activate switch key (joystick up or up arrow) in front of the soda machines for some free health." - TEM

"Use the phone in Chinatown and hear a little tribute to the film The Matrix.  Don't stop taking calls at the first phone, though, you'll hear references to other things at each phone you come across." - TEM

"Somewhere at the first level of "metro madness " you can find men's and a women's toilets. Get into the men's toilet for +10 of life by stepping outside and pressing the up arrow. Do it to the women's too. It's really worth it. "HAIL TO THE KING BABY!"" - ACE J.

"Right when your at the beginning there is a secret area behind you trust me it's hard to find at first." - tim

"try to use ur bombs and try bombing everi where for secrets.but save ur game b4 it." - kqq

"if u go left in the first level and then youl see the wall shoot ten patruns at it and then it brokes and there you can get lots of weapons" - sillu