ACHIEVEMENTS FOR EVERYONE!!!!
I won't bother rehashing what has been said over and over again (which is to say, the contents of the collection), but for those who haven't heard and/or are achievement hunters like myself, this game will test you.
The MCC will have 402 achievements
Halo: Combat Evolved Anniversary has 92 unique achievements worth 855G.
Halo 2 Anniversary has 111 unique achievements worth 1005G.
Halo 3 has 76 unique achievements worth 695G.
Halo 4 has 51 unique achievements worth 570G.
There's another 72 that AREN'T game specific, these can be earned across all games.
That's 402 achievements in total adding up to 4000 Gamerscore.
For the Hardcore Halo players, you'll have plenty of fun completing all the games with LASO enabled. Just be glad it isn't SLASO.
UPDATE: We were able to find the list. Here are all 402 achievements you can earn.
So, that is a hell of a lot of achievements – excited for them?