Small spoilers so far (nothing re the plot but just how the hunger games were back then)
Spoiler:
Tributes were shipped in animal crates to the capital and aren’t pampered like they were in the later books - they’re not even fed
This is the first time tributes are paired with mentors who are students at the Academy in the Capitol
This is the first time they’re given sponsors and gambling is introduced
Snow and Tigres are cousins
The arena is the old ampitheatre in the capitol, they dumb the tributes in there and leave them to fight, they just remove the bodies after it’s done there’s no clean up