The best replacement for mod is rocker.

The best alternatives to mod are rated as following:
★★★★★  rocker
★★★  mod
★★  ego
★  rem
★  full choke
★  hard mod
★  div
★  remainder
★  spawn
★  skinhead
★  lod
★  modulo
  minecraft
  admin
  soft mod
  immersive creatures
  midi
  hack
  amx mod
  dayz standalone
  standalone
  teddy boy
  intrastate mod
  l4d2
  quest sport

Your alternative for mod is not listed? Suggest!
Speaking about mod, one probably shouldn't forget about half life 2.

Other search terms related to mod and their ratings are:
★★★★★ half life 2
★ arma 2
★ fire and sword
★ hl2
You have in mind a companion for mod and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of mod in all years. Click on graph for more.
mod
rocker
mod