Vosaria: Lair of the Forgotten is a 2D side-scrolling action-adventure game. Players assume the role of a scout sent into the Vosari lair to locate a missing marine squadron. The core gameplay loop involves exploration and combat against the Vosari creatures inhabiting the subterranean environment.

Key mechanics include a unique jump-to-the-roof system for both combat and traversal. Players can discover and upgrade weapons, particularly through Alt-Fire enhancements. The game also encourages exploration to find hidden secrets and equipment scattered throughout the lair.