While Halo: MCC does offer Firefight today, it is actually the version that was part of Halo Reach, which was also just recently released as an expansion to MCC. The biggest difference between the two in terms of gameplay - in ODST you play as an ODST, not a Spartan - making the waves more difficult and dynamic. It is a more stripped down version of Firefight than what is found in Reach, but it just feels more "pure." 

Halo 2: Anniversary is a gloriously remastered version of the original Halo 2 (2004), initially released on Xbox One with Halo: The Master Chief Collection in 2014. Similar to Halo: Combat Evolved Anniversary, players can play through an enhanced version of the Halo 2 Campaign that features updated visuals and audio along with new Blur-created cinematics. Halo 2: Anniversary also includes an updated multiplayer experience featuring remasters of 7 iconic Halo 2 maps which include several different weapons and power-ups compared to the original game. Or, if you prefer to kick it oldschool, you can battle through the original Halo 2 campaign or jump into classic Halo 2 multiplayer across a total of 25 maps. 

Things will be handled a little differently based on platform, so we're breaking this out from here on out.

The campaign will hit sometime this May, tacking a few more gigabytes onto an already massive chunk of your hard drive.  Luckily, though, the campaign will be free to anyone who picked up the MCC on or before December 19th of last year.  Those who purchased the game after that point will be able to acquire it for an as-of-yet unspecified cost.

If we want to keep the metaphor going, the last month and a half would be the point of the movie where he's helping the town doctor save young Tommy, who he inadvertently caused to fall down a mineshaft for some reason.  By that, I mean that 343 Studios has been hard at work trying to fix the horrendous online issues plaguing the game.  Patch after patch has been released, but none seem to have the effect the developers intended. 

While the game is mostly better now, 343 understands the frustration that many have felt. While we've already seen formal apologies, now the gifts are going to begin flowing.