Boulder Dash II: Rockford's Revenge

Boulder Dash II: Rockford's Revenge is an action/puzzle game first released by First Star Software in 1985. It is the sequel to Boulder Dash and features similar gameplay along with all new levels. As in the original game, players control Rockford with the goal of searching dangerous caves for jewels.

Boulder Dash II presents players with 16 new caves to explore while maintaining the gameplay of the original game. Each of the caves is large enough to scroll across multiple screens and consists of empty space, dirt, boulders, jewels, walls, and in some cases dangerous creatures (including fireflies, butterflies, and deadly boxes). Players begin at the starting location and need to reach the exit before time runs out. Initially, the exit is closed; once players have collected enough jewels, the exit will open and players can enter it to proceed to the next cave. The number of jewels needed and the time available varies depending on the particular cave and the difficulty level selected. As players dig their way through the cave, any dirt that is dug through disappears and is replaced with open space. If any boulders or jewels are above or next to the newly created space, they will fall. This potentially can create a cascading effect as well where numerous boulders fall; if players are hit by any falling objects a life is lost.

Many of the levels in the game have some puzzle elements; players may need to be careful when navigating caves in order to make sure boulders don't fall and permanently block the path. In the event players become stuck and there is no way to complete a cave, it's possible to escape and start over again however this costs a life. In some cases, one or more of the creatures wandering the cave will need to be destroyed by dropping a boulder on top of it in order to reach the exit. Fireflies explode when a boulder falls on them; if near a wall, the wall is destroyed allowing players to proceed to a previously unavailable area. When butterflies are crushed by boulders, they turn into jewels; in some caves there aren't enough jewels present in order to open the exit without destroying one or more butterflies. Many caves also feature green amoeba; the amoeba slowly grows as time passes, filling any space not occupied by a wall, jewel, or boulder. If the amoeba becomes trapped by boulders and walls and can't grow any further it will turn into jewels. If the amoeba grows too large it will eventually turn into boulders. Players aren't harmed by the amoeba but can't move past it; successfully turning the amoeba into jewels is required to reach the exit in some of the caves.