As of 12-21-2001, Volition has seen fit to release the 1.2 patch for Red Faction.

You can find the news release describing this patch here.

The patch renders the techniques used by modders in previous versions obsolete. If you're curious you can still find this info here.

Unfortunately, it's still possible to cheat, to some extent, using a trainer. A trainer is basically an application you run prior to running Red Faction, which hangs out in memory. From playing around with one, my guess is that in response to certain keystrokes, the trainer tweaks memory locations on your machine related to weapon ammo and attributes.

Thus far, I've experimented with the Myth trainer with some success. In a multiplayer game, I was able to boost my ammo values for all available weapons, and further it appears that some reload attributes have been tweaked. For example, when I hit the function key for infinite ammo, then pick up a shotgun, I notice that when I hit my alt-fire key, the weapon fires constantly without having to reload after the usual 8 shots.

If you notice anyone in multiplayer seeming to have a freakin' lot of ammo, chances are they have a trainer like this one. Some of the features don't appear to work properly; for example, the Myth trainer offers an infinite life option as well, but it doesn't seem to work; I was still getting killed with a typical dose of damage.

Kudos to Volition for releasing this patch to combat cheaters. I may actually go out and buy the game as a token of appreciation for their response to this problem. It's a little late, but better late than never. :-)