The evil demon Crimson will not rest until humanity is destroyed. The powers of an ancient civilization made his resurrection more terrible than ever before: using robotic technology, he fused himself with a machine and became even stronger. Chosen heroes from different lands must meet each other and join forces to defeat Crimson once and for all.

Crimson III plays very similarly to its predecessor. It is a Japanese-style role-playing game with overhead navigation, first-person turn-based combat, randomly appearing enemies, and simple leveling up system. Like in the previous game, the player has to conclude initial chapters dedicated to each of the heroes before controlling them as a party on their main quest. Battles have an auto option, allowing the AI to take over the player-controlled party.