Book from 1960s or 70s similar to The Hunger Games where teens are forced to fight to the death

[Mara]

Might be a long shot but I'm trying to solve a mystery for my mom who can't remember the title of this book she read sometime in the 1970s. It involves a group of teenagers who are forced to fight for survival in this domed arena. Every so often part of the dome opens up and food is dropped in, and sometimes one of the competitors is taken out of the arena and possibly/presumably killed.

My mom described it as being really similar to The Hunger Games but can't remember anything else about it other than what I described above.

[Rainbowheart]

City of Darkness?

[Trilobyte]

Possibly The Tenth Victim - or the 7th victim or victim prime by the same author.

[Maggie]

Reminds me of House of Stairs by William Sleator. It’s like a psychological experiment and food pellets are dropped in randomly and of course they end up splitting into little factions and fighting for survival/dominance.