It would be interesting to see a DooM (2016) anime.
Marvel Land by Namco (Arcade/Mega Drive), Ghosts 'N Goblins, or Magician lord. But, Doom series would be awesome, too : )
Asuka 120% BURNING Fest., Mad Stalker: Full Metal Force and Panzer Bandit.
The star ocean series. Kingdom hearts
Definitely Sword of the Stars. It would make a pretty cool like space anime.
Threads of Fate, just for being a sentimental favorite that deserved to have an existence beyond just one game (especially since the ending cockteased the fans with the promise of a sequel).
I definitely agree with Zelda. I'm surprised it's never happened honestly. While I know one exists, I wouldn't mind seeing a new Fire Emblem anime.
Metal Gear Solid. :D