Stone Sling is the 20th official game released by Philips for the Videopac console. In the United States, it was sold under the title Smithereens! for the Magnavox Odyssey² console.
The game allows for two player simultaneous gameplay where both players have a fortress as well as a catapult used to fire each other. With each hit the fortress' size decreases by a bit. However, sometimes if your aim is off, the catapult will miss the fortress and instead hit one of the opposing soldiers. Like other Videopac games, Stone Sling could not compete against Atari games, though the game did do well in Europe and Brazil.
Heavily inspired by the sci-fi movie "Alien", you task is the capture or the killing of the alien on board your ship or the activation of the self-destruct sequence. In order to accomplish that you have to assign your crew memeber different tasks like accessing to the computer system, build weapons etc.
Alien Addition is an educational game that mixes maths problems with the gameplay of a shoot 'em up. The player controls a cannon left and right along the bottom of the screen and has to shoot down the aliens space ships that appear above him. There are five ships in a row and they slowly begin descending down the screen. Each ship has a maths problem written on it and to shoot it down the player has to enter the correct answer for the ship above him. The player is destroyed if any ship reaches the bottom. The game otherwise runs for a fixed time which can be customized by the player. Other customization options include skill level (1 to 9) and problem range (3, 6 or 9).
With the beginning of a new game, a map screen is shown with the player's position, as they control a ship set in a series of interconnected caverns. They must first plan out the best route in order to get to the central area in each Mission.
After several seconds, the map screen changes to a cavern that the player is currently in, which each cavern has a core in the center that is constantly growing, as well as having several Planet Protector enemies. It is usually in the player's best interest to clear out each area of Planet Protectors by shooting them, then carefully inching their way to the protective barrier by an exit in order to drill through it. Once the barrier has been disabled by the drill, the player can then fly into the next cavern and thereby gets a step closer to the central area.
The view changes from a cavern to the map screen with each cavern that they pass, showing the player's(') progress. Once the central central area is reached, the player(s) must drop a bomb at the center core, which they