Well, you could have a plot where a group of tributes decides to rebel against the Capitol's rules from within the arena. They try to find ways to communicate with the outside world and start a revolution. Also, a story about a tribute with a disability who overcomes all odds in the arena through sheer determination and cleverness.
A possible plot idea is a love story between two tributes from different districts. They have to balance their feelings with the brutal reality of the Games. Or perhaps a tribute who is an artist and uses their creativity to outwit the other tributes, like creating decoys or traps using their art skills.
One idea could be a fanfiction where Peeta and Gale are forced to team up as tributes in an alternate version of the Hunger Games. They start off distrusting each other because of their rivalry over Katniss, but as they face the challenges of the arena, they realize they have to rely on each other's skills. Peeta's charm and ability to manipulate the Capitol's favor could be combined with Gale's hunting and survival skills.
One idea could be a tribute who has a unique survival skill like being able to communicate with animals in the arena. They could use this to gather information about hidden resources or approaching threats.
One idea could be a revolution within the 100th Hunger Games. The tributes from different districts secretly plan to overthrow the Capitol's control over the games. They start by forming alliances not just for survival but to spread their message of resistance among the other tributes.
One idea could be focusing on a new type of arena. For example, an arena that changes based on the tributes' worst nightmares. This would add a psychological twist to the games.
One idea could be to focus on a new type of arena, like an underwater arena. The tributes would have to deal with things like limited air supply and underwater predators. Another could be a tribute from a previously overlooked district who has some unique skill, like being able to communicate with animals, which gives them an edge in the games.
Another plot could revolve around the Capitol's perspective. Show how the Gamemakers manipulate the Games, not just in terms of the physical challenges but also in influencing the tributes' mental states. For example, they could use propaganda within the Capitol to create more hype around certain tributes.
One idea could be a story focusing on an underdog tribute who has a unique skill like being able to communicate with animals. They use this skill to survive in the arena, forming alliances with the creatures there. Another could be about a group of tributes from a previously overlooked district who band together and use their collective knowledge of their district's unique environment to outwit the others. Maybe a story where a tribute is haunted by the ghosts of past Hunger Games participants, and has to overcome both the physical challenges of the arena and the psychological ones of these apparitions.
One idea could be to focus on a new type of arena. For example, an arena that changes based on the emotions of the tributes. If a tribute feels extreme fear, the part of the arena they are in could transform into a more dangerous place. Another could be to have an alliance of underdog tributes who use their unique skills, like one being great at camouflage and another at finding water, to outwit the stronger tributes.
Another plot could be about a group of tributes who form an alliance not just for survival in the arena but also with the intention of overthrowing the Capitol's control over the games. They could use their skills and the element of surprise to try and expose the cruel system from within the Hunger Games itself.
Katniss and Peeta are often very popular. Their relationship and the whole star - crossed lovers thing makes for great fanfiction. People love to explore different scenarios for them, like what if they had met before the Reaping.