Mountain Defender is tower-defense game that tests a player's hand-eye coordination and physical speed. The game tasks the player with protecting a giant, blue crystal that floats above the pinnacle of the mountain home of the Greek gods (Mount Olympus) from monsters sent from the pits of Hades to destroy it.
The top of the mountain features multiple towers and structures positioned on grassy hills. The monster soldiers initially climb stairs leading to metal gates and open doorways in the towers. In later waves, they ride dragons. The player uses a virtual hand to physically pluck each enemy combatant from the mountain and toss them into clouds hanging near the bottom of the screen.
With each successful toss, the player receives coins that make it possible for them to use powers of the gods to destroy more enemies faster. These powers include an ice storm that freezes enemies into solid blocks of ice, an earthquake that shakes enemies off stairs, landings and balconies and fiery meteorites that knock flying soldiers and their dragons from the skies.
Mountain Defender tracks the player's progress. On the home screen, the player can access a top 100 leaderboard that displays the ranks of other players and their rank highlighted at the bottom of the board.