Combat Evolved and 2 were the only ones that mattered so.....
Only ones that mattered...to what?
It is my opinion that those two are the only ones to have any major impact-not just on the franchise; on gaming as a whole.
Halo:Combat Evolved is why the original Xbox did so well and that was the base of the 360'd development. Think of what The Mario games did for the Nintendo name. What pac man did for Atari. Sonic for Sega. Etc. etc.
Halo 2 laid a ton of the groundwork for Live.
Yes, other games took parts in these events but at that time none had a greater impact.
You could say fable helped with the original Xbox. You could say oblivion helped the 360 at release. But the halo franchise had key parts at those times.
I think that's mainly due to Bungie. Look at Reach when 343i took over. Look at Halo 4.
Yeah bungie released some not so great halo games, but the good out weights the bad. A million fold.
The official Sheogorath of The Elder Scrolls V: Skyrim. The right and Righteous hand of Whatnos