If you don't mind RPG maker games or Dubcon, Futanari Alchemist Triss is pretty good. The combat is as generic as you would expect, but the scenes definitely hit in all the right places, for me anyway. Like Lipstor said, Futa games are pretty rare, especially good ones unfortunately.
Some other games would be:
Explorer of the Golden Planet, a 2D adventure game. There's no proper translation for the game, which is criminal. You get the Futa attachment about halfway through.
Max the elf, a femboy sidescroller
Futadom world, a renpy game with futa on male, if you're into that.
Captivity, a side scrolling action in the style of COD zombies. Only one stage features Futa FNAF enemies, the rest being zombies and dogs, aliens, bugs, and goblins.