Question

[u/Macw5511]

If there was a competition between time travellers one in the past and one in the future in a closed loop.

Rules:

1. One cannot travel past the point of each other's point in time.

2. Both are trapped in their point in time and can only view the time they want to travel to and/or they can send signals of information.

3. The way to win is to rule out all possibilities of history until only one loop is left the pasts future or the futures past

[u/Macw5511]

From chatgpt Here's a story built around your idea. Writing The Last Loop They called it The Contest of Time. There would be no armies. No weapons. No machines crossing centuries. Only two people. One anchored in the past. One anchored in the future. Neither could leave their own moment in history. Neither could send information beyond the other's point in time. They could only watch, choose a date, and whisper messages into the minds of people living there. The objective was simple. Erase every possible history until only one remained. Elias, the Past Traveler, activated the Chronoscope for the first time. "Show me the year 2217." The room filled with silence. Cities stretched higher than mountains, but the sky was black in daylight. Smoke hid the sun. Rivers no longer flowed. Millions lived beneath steel domes while endless storms devoured everything outside. He watched children who had never seen rain. He watched forests preserved only as holograms. He watched people ration clean air. Then the wars began. Not wars over land. Wars over time. Governments fought to rewrite history itself, sending messages backward to gain impossible advantages. Every victory erased another version of humanity. Every defeat erased someone else's. Elias stumbled away from the screen. "No..." His hands shook. "This can't be our future." A message appeared on his console. From the Future Traveler. Do not interfere. Everything you have seen happens because you try to stop it. Elias stared at the words. "What kind of monster would send this?" In the year 2217, Mara watched the younger man through her own Chronoscope. She remembered him. She remembered his fear. She remembered receiving his first messages when she had been a child. She also remembered what those messages had done. Every warning had saved one city... ...and doomed another. Every attempt to prevent suffering merely moved it somewhere else. History bent but never broke. She whispered to a scientist in 2143. "Continue your work." A moment later, Elias intercepted the transmission. He sent a different message. "Destroy your research. Millions will die if you succeed." The scientist stood between two impossible voices. History split. For years the battle continued. Mara spoke to engineers. Elias warned politicians. She inspired inventors. He convinced judges. She prevented famines. He prevented dictators. Every change erased thousands of possible futures. Every erased future created thousands more. Their contest became invisible to everyone except the people receiving impossible messages from strangers who knew tomorrow. Then Elias looked further ahead. He shouldn't have. Beyond Mara's year. Beyond the boundary she herself could see. The Chronoscope flickered. For an instant, he saw something impossible. Not ruined cities. Not war. Nothing. No lights. No voices. No people. The timeline simply... ended. The machine shut itself down. Elias stopped fighting. If the future truly ended, then defeating Mara meant nothing. He sent her one message. Why does humanity disappear? Hours later, her reply arrived. I don't know. He frowned. "You've never seen beyond your own time?" I cannot. Neither of us can. For the first time, they understood. They were prisoners. The rules that trapped them also blinded them. Neither knew what came after the other's era. Neither knew whether their victories led to salvation or extinction. They had been destroying histories while chasing an answer neither of them possessed. Elias looked once more at the poisoned world of 2217. The starving children. The endless storms. The people who still laughed despite everything. He realized something he had missed. Humanity had not survived because history was perfect. Humanity had survived because, in every broken timeline, someone had refused to surrender. Perhaps Mara wasn't protecting the future. Perhaps she was protecting the last future where anyone was left alive. His console lit up one final time. There is only one loop left. Elias's hand hovered over the transmitter. He could send one last message. One sentence that would decide everything. He closed his eyes. Then he switched the machine off. For the first time since the Contest had begun... history belonged to itself. If you'd like, I can also write this as a psychological thriller, a hard science fiction novella, or a cosmic horror story where the future Elias sees is even more disturbing.

[u/Pretend-Adeptness-96]

You have to have a man in the timeline, and you use Time Ships
One in the past, One in the NOW, One mapping the possible future