Lockstep is not as gargantuan as either of those, but it is a genuinely new idea for a hard-SF civilization. I didn't think any of those were left. Come to think of it, the last one was Schroeder's Permanence, unless it was Schroeder's Virga books. I guess he's chosen a metier.
I will not describe The Gimmick. It's not a book-length secret (it's explained in chapter 2) but if I get into it I'll derail into a discussion of how clever and/or plausible it is, and so what. I think it's very clever and mostly plausible. Totally plausible enough for 70s or 80s or 90s wacky-idea SF.
The story is intertwined with The Gimmick, but it's not a gimmick story. It's a story about a kid named Toby McGonigal, caught out of time by a hibernation accident, trying to survive in a world gone mad. (From his point of view.) (Okay, when people start worshipping him as the Emperor of Time, that's pretty mad by anybody's standard.) I originally wrote "boy hero Toby McGonigal", but that's wrong; he's an ordinary kid forced to cope with circumstances. Like I said -- classic. Carried off perfectly well. I liked it.
Looking back, I can say that that this book has a better-structured plot than the Virga series, a better ending than Lady of Mazes, and the Big Idea is solid. This makes it Schroeder's best book overall, even if I can name individual scenes in earlier books that I enjoyed more.