99'Vaders

99'Vaders for the Texas Instruments TI-99/4A is a variant of Astro Invader, an arcade shoot 'em up where aliens are released from a mothership and positioned in columns before attacking. When one column is full the aliens will start descending, one at a time, and explode upon reaching the bottom of the screen. If the player's ship is within the blast radius it will be destroyed and one of three lives are lost. In addition to the regular aliens, there are also deadly vessels which fall from the ship's side chutes and will kill the player no matter the position. When a certain amount of aliens have been killed the mothership takes off and another harder one will take its place. As it leaves it is possible to shoot its exhaust tube for extra points.