Real quick thoughts here so I don’t forget to talk about them later: D20 Modern is a tabletop game designed by Wiards of the Coast to use their 3rd Edition D&D rules as a basis for tabletop gameplay set in the real world or in some modern equivalent.
Now, it didn’t do well probably because of a number of reasons, not the least being that the game had to run up against some pretty fearsome competition in the let’s-play-with-guns, modern-urban-maybe-fantasy storytelling system, but I think the system has a deeper flaw running through the design of the game itself.
D20 Modern has no idea the kind of game it wants to be.
If you want to represent the world of Fargo, Snatch, The Ipcress Files, Kiss Kiss, Bang Bang, Animorphs and Buffy The Vampire Slayer all at once, with one central set of mechanics, you’re going to stumble. Mechanics are very important to storytelling – either as metaphor, or in showing what players shouldn’t worry about, and D20 Modern doesn’t know what its mechanics are trying to do.