The TI-99/4 seems to be missing a lot of the arcade classics. I'm not familiar with all the TI games so some of these might already exist.
Does the TI-99/4 have any versions of these that are somewhat true to the arcade?
Phoenix, Wizard of Wor, Gorf, Galaxian, Galaga, Missile Command, Rally X (Radar Rat Race), Moon Cresta, Gyruss, Satan's Hollow, Spy Hunter, Joust, Sinistar, Track & Field
Some vector games might be a stretch but... Battle Zone, Asteroids, Asteroids Deluxe, Omega Race, Star Castle, Black Widow, Star Wars, Star Hawk, Tail Gunner
Some computer games that might be worth porting:
Gremlins, Drol, Wavy Navy, Eastern Front 1941 (last I saw the current port was unfinished), Starship Command
Are there any isometric games on the TI? They tend to be memory hungry so maybe not the best choice but it would be nice to see at least one on the 99.