Read-only feature:
Get Aeon Reserve Tank (refills gauge when empty) / After beating game: Unlock Metroid II art
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Read-only feature:
Place a Metroid Marker (see closest Metroid on map) / After beating game: Unlock Fusion difficulty mode and play with Fusion suit
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Read-only feature:
Get Missile Reserve Tank (replenishes missiles when empty) / After beating game: Unlock concept art
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Read-only feature:
Get Energy Reserve Tank (replenishes health when empty) / After beating game: Unlock Sound Test mode
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