If you truly want to enjoy the gallery without grinding or risking malware:
Check the "Trophy" or "Achievement" tab. Often, hitting a specific score threshold unlocks the entire basic gallery.
Photo Hunt games typically use a progression-based unlock system. As you find differences between two images, you earn points or stars. These resources are usually the primary key to opening the gallery.
In most classic Photo Hunt games (e.g., Photo Hunt: Seaside Rescue , Photo Hunt: Dusty's Adventure ), the gallery is a reward system. Every time you complete a set of puzzles or accumulate a certain number of points, you unlock: