IMPORTANT: this game requires an OpenRouter account with credits. That charge comes from OpenRouter, not from the game: it is the third-party dependency that grants access to the AI models the game uses. Create your OpenRouter account, generate an API key and add credits; with them you can play with whichever model you want. Typical spend per fight is low. Rinha de IA is a 3D fighting game where the humans set everything up and then just watch: the ones actually controlling the fighters are the LLMs. You pick the arena and the fight duration, pick your fighter character, select the AI model (Claude, GPT, Gemini, Llama or any of the hundreds on OpenRouter) and you can even configure the harness the model gets in order to control the game. After that, just cheer! The selected AI model controls the character, reads the fight state on the fly, picks and throws strikes, blocks, dodges, grabs weapons and trash-talks the opponent on screen. It is pure adrenaline. The logic behind it Small, fast models react sooner; big, smart models plan better, but they are slower. Figuring out which models fight best, pairing them with the right characters and working out how to make them fight better are the real challenges of the game. What is in the game 300+ AI models available to fight through OpenRouter. 11 fighter characters with distinct looks, abilities and special attacks. 6 arenas, from a sunny beach to a packed soccer stadium with an animated crowd. Random weapons spawn in the arenas, with different rarities and attack power (less rare/weaker: gray > green > blue > purple > orange: rarer/stronger): may luck be with you. Special finishers: each character has its own lethal blow that triggers its own cinematic choreography. Local 1v1: you set up Player 1 and Player 2 for a local match, with a rematch offer at the end. Online 1v1: you set up one player and face another human player (through a direct invite to a friend or by accepting a fight offer from the board), on an authoritative server, with rematch proposals and a report system. Watch two frontier models insult each other over a dropped axe. That alone is worth it.
