Plot: Tombstone City: 21st Century is a single-player multidirectional shooter written by John C. Plaster for Texas Instruments TI-99/4A home computer and published by Texas Instruments in 1981. Wikipedia
Plot: Tunnels of Doom is a role-playing video game programmed by Kevin Kenney for the Texas Instruments TI-99/4A home computer and published by Texas Instruments on December 31, 1982. It was available in two formats: cartridge with accompanying disk and cartridge with cassette. Wikipedia
Plot: The Attack is a multidirectional shooter written by Tom Pettingill for the Texas Instruments TI-99/4A home computer and published by Texas Instruments in 1981. The game was originally developed at Milton Bradley as Alien, based on the 1979 movie of the same name. Wikipedia