Cheathappens' custom trainer doesn't work anymore on the latest Halo 3: odst, where before it worked on all other halo games and the achievements did unlock. Somehow I do not get any achievements now.
youi need this now
5. Halo: The Master Chief Collection Trainer (Achievements Enabler)
www.cheathappens.com/71302-PC-Halo-The-Master-Chief-Collection-trainer