In the GBA version of Bionicle Heroes, based on the LEGO Bionicle franchise, players take on the guise of the TOA Anika team. Set on the island of Voya Nui, they need to retrieve the Mask of Life, stolen by the Piraka race who also enslaved the Matoran, the native inhabitants, in the process. Unlike the console and the DS versions, a top-down perspective is used.
The game takes place on six zones of the island, followed by a final showdown. The player starts as a TOA of Fire, but by completing zones and killing the level boss, additional masks can be collected: Air, Stone, Ice, Earth and Water. Each TOA has a primary and secondary weapon based on the mask's elemental nature, with specific features. During the levels, there are also weapon upgrades to be found. The second weapon is limited by an energy meter which needs some time to recharge. Each zone requires a specific TOA guise, but in the Free Play mode completed levels can be revisited and players can then switch between the forms at any time to use different abilities. TOAs can strafe while fighting - there is an option to face enemies automatically or to control this manually.
TOAs are assisted by proto-spawn orbs, sidekicks that circle around the hero and fire at enemies. The orbs are chased off when they take too much damage, but they can also be upgraded based on the 6 elements and the weapons can be customized. Players can define to have the orbs fire in spread patterns or rapid bursts, lock on targets with fire, cause explosions, fire through shields or do double damage. Additional attacks are provided through elemental runes, which provide a one-time limited effect, such as freezing enemies, activating a lightning shield, smashing enemies with spikes from the ground, temporary invulnerability, full health and regeneration, and a fire blast.
By destroying objects and buildings in the environment, blue, gray or gold LEGO pieces are revealed, providing health and bonus points. The TOAs also need to use pieces to build bridges, platforms, elevators, turrets, barricades or moving platforms. At the end of each zone, the rank and score is shown. Based on the performance or specific actions, there are 12 medals to collect, of which a few can only be found in the Free Play mode.
Each zone contains secret cheat words. Upon discovering them, they are added to a cheat menu. They allow to play as a golden TOA or to obtain a new mask with a sombrero, open up a music jukebox, provide a hidden Cluck gun or grant invincibility or one-shot kills.