The best replacement for halo 2 is halo 3.

The best alternatives to halo 2 are rated as following:
★★★★★  halo 3
★★★★  half life 2
★★★  halo 1
★★  killzone
★★  halo 3 graphics
★★  halo
★★  halo reach
★  san andreas
★  halo combat evolved
★  gta san andreas
  grand theft auto san andreas
  doom 3
  glitches
  grand theft auto
  metroid prime 2
  combat evolved
  jaybird sportsband

Your alternative for halo 2 is not listed? Suggest!
Speaking about halo 2, one probably shouldn't forget about action replay.

Other search terms related to halo 2 and their ratings are:
★★★★★ action replay
★ xbox
You have in mind a companion for halo 2 and it is not yet here? Propose!



Google Trends

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halo 2
halo 3
half life 2