Radio Controlled Helicopters

I have seen these model helicopters that are even able to fly ‘up-side-down’ and in all directions…. they seem to be very powerful . Some even eject some form of ‘gas’ so i guess it has an engine.

can you please tell me to what ‘category’ these helicopters belong to.
If i go to a toy-shop saying what name should i ask for one?

Exactly what you said.
Do a Google search on ‘RC Helicopters‘ and you will get lots of returns. There are videos at hobby club web sites showing these flying.