Atarisoft

Donkey Kong is a platform game that requires the player to cross numerous platforms and scale ladders to ascend to ever higher platforms before reaching the goal of each stage. Donkey Kong was also one of the first games of this genre to require the player to jump over various obstacles including gaps, barrels, and fireballs. The ultimate goal of each level, and the entire game as a whole, is to help Mario ascend to the uppermost platform of the stage to rescue his girlfriend Pauline from the clutches of the gigantic ape, Donkey Kong. There are up to four stages to each level

Defender is a two-dimensional side-scrolling shooter. It occurs on the surface of an unknown and unnamed planet. The player can move his/her ship left or right and up or down. The player's goal is to destroy as many alien invader's spaceships as possible and to prevent them from abducting the humanoids on the surface of the planet. When the player destroys all the enemies, he/she advances to the next level. The player loses a ship when it gets hit by enemy fire or if hyperspace jumps go wrong. The game ends when the player loses all his/her ships. 

Dodging and blasting Pookas, and dropping rocks on fire-breathing Fygars; Dig Dug burrows his way through a maze of subterranean paths. Ripe fruits and veggies, loaded with points, are his passion. But the evil denizens of the underground pack a potentially lethal wallop, and can hide behind fruits. Even when Dig Dug kills them they may come back as Ghosts. Ghosts don't need tunnels and are harder to kill. Luckily, when the chips are down, they turn out to be cowards. . . and worth points. 

You  control a robotic detective of the same name through a 128 room maze with electrified walls. The player is in search of his ultimate enemy, "The Shadow" hidden somewhere within the 128 rooms. To achieve this goal, the player must collect certain color-coded keys which open the same color-coded locks allowing the player further advancement towards the ultimate goal. Enemies that the player will encounter during his travels include spiral drones, robo droids, and snap jumpers, each intent on destroying the player.

The player in Moon Patrol plays as a volunteer police officer on Sector Nine, known as the home of the toughest thugs in the galaxy. The player controls a lunar buggy vehicle over the surface of the moon from a side view. The vehicle travels from left to right during gameplay. The player faces many obstacles along the way including craters, mines, and missiles from overhead UFOs. These missiles also create new craters that can make for a unique situation when they hit immediately in front of the player.

You control Pac-Man through a maze filled with little dots. There are four enemy ghosts bent on catching Pac-Man, resulting in the loss of one life. The player's goal is to clear the little dots by eating them, completing the level and sending the player to the next level, all while avoiding those pesky ghosts. There are four larger, flashing dots called "energizers" of "power pellets." When Pac-Man eats an energizer or power pellet, he turns the tables on enemy ghouls allowing him, for a limited amount of time, to eat the ghosts.

Jungle Hunt consists of four unique levels of play called scenes. Scene one is the jungle scene. The player on this level has to swing from vine to vine, timing each jump from one vine to land perfectly on the next. Scene two is the water scene. The player swims through a crocodile-infested river. Scene three is the rock scene. The player dodges multiple-sized boulders that roll and bounce towards him as he/she runs up the side of a volcano. Scene four is the native scene. The player attempts to rescue a woman who is being lowered into a flaming cauldron while evading cannibals that have her captured.

Ms. Pac-Man plays similarly to the original Pac-Man video game. Points are earned in much the same manner, by eating pellets to clear levels, all while avoiding the ghosts. Running into a ghost leads to the player losing one life. However, when the player runs over or "eats" an energizer or "power pallet," it turns all ghosts blue, meaning they are vulnerable to being consumed by Ms. Pac-Man. Each ghost eaten consecutively increases the point value. Occasionally, fruit or other or pretzels appear in the middle of the board that also give the player bonus points. 

The player in Pole Position controls a Formula 1 race car as it hurls along the racing speedway at Fuji Racetrack. To begin, the player has to qualify during a time trial lap. The player must complete the time trial between 57 and 120 seconds to qualify. Based on the time trial completion time, the player is placed in the field of 8 racers from either the pole position or position 1, to position 8. As the player races, he/she must avoid crashes with other racers, and keep from veering offroad where billboards await to destroy wayward racers. 

The player in Picnic Paranoia controls "George" who attempts to protect a picnic from ants who try to carry off the food that has been set up on picnic blankets, spiders who weave webs to slow George down and bite him, and wasps that sting and paralyze him. The player must also try to replace food back onto the picnic blankets after it has been removed by the ants. Points are awarded for each item of food remaining on the screen at the end of each round. Rounds last for 90 seconds. The game ends when all the food is removed from the screen. There are sixteen levels or rounds to Picnic Paranoia. 

Robotron is a 2D multidirectional shooter game in which the player controls the protagonist from a top-down perspective. The game is set in the year 2084 in a fictional world where robots or Robotrons have conquered the world and eradicated most of the human race. Each level, referred to as a "wave", is a single screen populated with a large number of various enemy robots and obstacles; types range from invincible giants to robots that continually manufacture other robots that shoot the protagonist.

The player in Protector II pilots a spacecraft called the Neeedlefighter ship. The goal is to rescue the 18 stranded survivors from the surface of the planet. This rescue occurs in stages with no apparent transition between stages. First, the player moves the player from their original location to the top of the buildings in the City of Hope. From there, he/she must continue to move them to a portal that is blockaded deep in the Verdann Fortress. The player starts 6 Needlefighters and loses one for each hit with an enemy spacecraft or bullet. The transport of the survivors occurs one at-a-time. 

Special thanks to 4apedia.com for helping me with most of the game descriptions. Please visit this excellent page for more TI-99/4a information