Worldmodelgym

Reka AI's WorldModelGym tests whether a model's imagined futures help it choose useful actions. A world model predicts what happens after an action. In Reka's July 2026 benchmark protocol, it predicts the outcomes of five supplied action sequences and selects the one with the highest predicted reward. The evaluator compares that choice with outcomes already measured in the underlying test environment.

A second measure checks the predicted rewards themselves, helping distinguish accurate forecasting from a lucky choice. Together, these tests assess whether a simulator supports decisions. Because the action sequences are fixed in advance, continuous replanning as new observations arrive remains outside the test.