I’m pretty new to this online multiplayer stuff, i’m curious to know, i have the ODST game as well as 3, can you unlck the Halo 3 online achievements through ODST?
Using the Halo 3 Mythic disc?
Yes, you can indeed!
Yes i’m using Mythic disc,
Thank you that’s answered my question 
alright, let’s get a Mod in here an lock this up.