The Eschaton section is freighted so awfully damn heavily with explicit and implicit reference and symbolism, you have to wonder how seriously DFW was taking the enterprise as he wrote it.
You've got the map/territory discussion internal to the game reflecting the map/territory questions out there in the world of the novel. You've got the map-as-life or map-as-face thing going on which now has another facet altogether as we need to wonder, if "eliminating one's map" is suicide, then what territory does that map refer to? How much does the formation of O.N.A.N. and the Great Concavity/Convexity involve actual changes to territory vs. changes to maps? Which are people actually fighting over?
Having the role of "God" in the game played by Otis P. Lord is about as subtle as a flying mallet, and calling him "O. Lord" just makes it worse, but it's kind of an interesting exercise to read some of the exchanges as prayers and responses. And finally you get God's head stuck inside a monitor.
But also notice the last sentence about Hal: "For a brief moment that Hal will later regard as completely and uncomfortably bizarre, Hall feels at his own face to see whether he is wincing." There it is, in a flicker, a half-acknowledged moment of recognition that something's wrong, that there's a disconnection between what Hal thinks and feels or what he thinks that he feels and what he displays to the world.
Oh, and I've read but cannot recall where, that the math in Endnote 123 has some serious flaws, which some think must have been deliberate given DFW's mathematical competence (displayed elsewhere, I guess).
The kids' obsessive study of the game and its documentation were spot-on as far as I'm concerned. Certainly my D&D buddies and I back in college devoted far more time to the study of the Monster Manual than any of our texts, and I bet there are plenty of you out there who as kids memorized absurd quantities of equivalent information.