Riddley Walker was probably also a big influence on Iain M. Banks' Feersum Endjinn [1]. Most of the chapters are narrated by Bascule, a simple-minded (but certainly not stupid) young man who writes phonetically:

  Woak up. Got dresd. Had brekfast. Spoke wif Ergates
  thi ant who sed itz juss been wurk wurk wurk 4 u
  lately master Bascule, Y dont u ½ a holiday?

The novel is a bit out of character for Banks, and reminds me of something Gene Wolfe or Terry Pratchett might have come up with. I think it's a wonderfully underrated gem, and Bascule's narration is one of its endearing features.

[1] https://www.amazon.com/Feersum-Endjinn-Novel-Iain-Banks/dp/0...