Brigitte Bleu began to rule the world after the imprisonment of General Plastro. She tries to get rid of her rival Vicki in order to get hold of her sweetheart Sarge. However, Vicki has other plans in mind. Teaming up with a friendly lion named Leo, she embarks on a quest to end Brigitte's reign once and for all.

Portal Runner is a 3D action game with puzzle-solving elements, and a spin-off in the Army Men series. There are five worlds to travel to in the game. Environmental puzzles, platform jumping and battles against enemies constitute the bulk of the gameplay. Vicki can shoot arrows at the enemies, and strafe to avoid their fire. Leo can be controlled either indirectly, by issuing orders to him, or in exclusive stages where he fights using his claws. Some stages feature Vicki riding Leo.