Why is Halo CE and Halo 2 not compatible with the Xbox One, X|S?

Yeah, You can get:

Halo CE (Original Xbox Backward Compatible)

Halo 2 (Original Xbox Backward Compatible)

Halo 3

Halo 4

Halo Reach

Halo 3 ODST

Halo Wars

Halo Spartan Assault

Halo CE Anniversary

Any of these can be played solo, and offline if you wish.

The Original Xbox version of Halo CE is only backwards compatible on the the 360
To play it on the One X you would need Halo The Master Chief Collection which includes
Halo CE Anniversary

Halo 2 Anniversary

Halo 3

Halo 3 ODST - available as add on content

Halo Reach - available as add on content

Halo 4

And at the moment it is HALF PRICE in the Microsoft store (with ODST and Reach included too)

Buy Halo: The Master Chief Collection - Microsoft Store en-GB

Halo 4's campaign was ok, nothing more, imo.

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1. Halo: CE

2. Halo 3

3. Halo 2

4. Halo: Reach

5. Halo 4

6. Halo: ODST

no...halo 4 is the 9th?. you're forgetting the pc versions of halo ce and halo 2

halo ce

halo ce for the pc

halo 2

halo 2 for the pc

halo 3

halo odst

halo wars

halo reach

halo 4

With the new CE Anniversary I would start there. It is the start of the Halo trilogy. There is the Halo Wars game, which is a RTS style game (think Command and Conquer) and it takes place before CE, though most won't consider it part of the MC line. And
Halo 2 is an Xbox original title, but it is backwards compatable with the 360. Just the mp nolonger works. Then the Halo 3 is the final game of the MC trilogy. You can find it used at GameStop or Ebay for $5. Halo Reach is also a good one and is sort-of tied
to the MC trilogy. It takes place before Halo CE and where it ends is where CEA begins. Hope this helps.