Advance Guardian Heroes is a side-scrolling, beat-em-up action game that follows the sequel to Guardian Heroes for the SEGA Saturn. You choose from 3 characters who will be joined by a legendary Soul Hero from another world. You must take control of the Legendary Soul Sword from the Soul Hero's grave and save the world.
The game features two main modes: Story mode and VS. mode. In Story mode, you can play solo or with a friend by linking two GameBoy Advance consoles together. In VS. mode, up to 4 players can battle each other. As you progress through the levels, you receive crystals from defeated enemies. You can also upgrade your character's traits like MP or HP at the end of each level.
Additionally, you can donate to the Laboratory, which will eventually unlock new characters for VS. mode. There are 3 initial characters available, but up to 20 more can be unlocked through gameplay and upgrades.