While all four of the Mortal Kombat games have been released on Nintendo's portable platform, none of them have been terribly faithful re-creations of the arcade games on which they are based. I mean, let's face it: It's hard to take all those digitized graphics and toss them onto the Game Boy. Tossing the 3D environment of the fourth game would be nearly impossible. So MK4 on the GB is a strictly 2D affair.
Many of the original game's characters have been stripped out, and the move count has been greatly reduced. Much like the other MK games on the Game Boy, the controls aren't very responsive. Special moves are a chore to pull off.
The game's fatalities are done a bit differently than the fatalities in the previous games. When you perform the move, the game cuts away to a short, grainy animation, presumably digitized from the arcade version. It's a nice, quirky touch that brings a little charm to an otherwise uneventful game. People looking for portable fighting-game action would do well to wait for Street Fighter Alpha, a much more responsive fighting game.