Matrix Upgraded is not so much a mod in itself, more a collection of mods by various authors - including Kung Fu Version 3 - tied together in unison. Matrix Upgraded brings dozens of weapons to the game, mostly those from the Matrix movies and a couple of others for good measure and it also includes a couple of the fights from the movies - the Chateau battle between Neo and the Merovingian's goons and the far more entertaining lobby scene from the original Matrix.
The Matrix Upgraded mod also allows you to visit any of the levels in the original game and take them on, although as you are playing a Neo rather than Max, your moves and weapons are a couple more orders of magnitude more over the top than even in the Kung Fu mod, and much of the classic ambience is lost.
The Katana Mod is more of a complete conversion than any of the others listed, as it does away with the original levels completely. The new story drops you into the role of a jaded assassin who, having walked away from his past and his organisation, now has to deal with the consequences. The consequences naturally being that in return for his desertion, his former comrades want to chop him up into very fine strips with very sharp swords.
Katana offers a different combat system to the original Max Payne and to the other mods we've looked at, providing a Jedi Knight style sword fighting system including combos, parrying and an array of moves some easy to implement, some more complex. The sword is complemented by a range of weapons and although there is no explanation given for how you can use dual pistols while you've still got a sword in your hand, this isn't really a deal breaker. The Katana mod is an impressive departure from the original game.
Installing mods for Max Payne could not be simpler and is one of the key reasons it is worth trying - unlike some games that require shortcut tinkering and irreparable changes to the original files, Max Payne relies simply on adding the mod file to the main directory, then selecting the mod you want to use on the launcher menu.
It is about as simple a system as you are likely to find, making it an ideal game for those who are new to the whole modding process. Thanks largely to the age of Max Payne and the age of most of the mods, while many feature some pretty large scale fights and bigger guns this is generally nothing that should really hit the framerate of a modern gaming computer and despite some squareness to the characters, with the graphics cranked up good and high the game still looks good.