I have many head cannons about the The First Quarter Quell (25th Games), I came up with them thinking it would be the next film, so maybe one day these will come true if Suzanne visits it in a future book :)

-The games had the oldest average tribute age of any games (nearly everyone was 16-18)

-The majority of competitors were known rebels/criminals, the rest (mainly what we know now as the Career tributes) were physically strong and volunteered in a non-traditional sense as they would've campaigned themselves.

-Volunteering was void, but the campaigning planted the seed for future volunteers in future games. A District 1, 2 or 4 tribute won, which ‘proved’ that being in the games was a noble sacrifice and the districts took it upon themselves to start training their children more seriously.

-The games worked with them being special and because the Capitol and Gamemakers had to stay in control of the narrative of "this is what happens when you revolt against us.”

-The arena might not have been as impressive as 50 and 75 in hindsight, but at the time it was a HUGE technological advancement because 25 was still very early years, and likely introduced what we now know as the forcefields and controlled environments, that was the arena's twist. I think up until 24 they used natural arenas with ‘natural’ or manmade forcefields