Ever since I saw that rollerskater in Vice City all those years ago, I also want skates. A skateboard too would be awesome.
Other things that I've seen in much older video games:
- Dual wielding weapons (this was a feature in True Crime games). A katana and a gun would be sweet.
- Limb deformation (this was a feature in GTA:VC and JediAcademy games)
- Chill pedestrians. The simple ability for a situation not to escalate.
- Children. I just want to know that they can exist. Happily teleport them away if they're in danger.
- Waterskiing.
- Kite-surfing
- Slow-motion toggle in single-player mode. Sometimes you want to appreciate the spectacle of the simulation.
- Seamless interiors. I want to dive out of a skyscraper window.
- A hard to fly jet pack. It should not be easy, or stable.
- Car bombs (was a feature in GTA2 and GTA3)
- Deformable landscapes. Not permanent, but if I bazooka the ground, there should be a trench.