How can cooling gases do not change their physical states?
Well since the lowest temperature that can exist is -273.15 C.

All gases condense to liquid or solids almost all to solids because at this temperature molecular activity ceases.

And the title of your question seems contradicting with what you have written. Probably you might have mistaken interpreting "before".

also only ideal gas can remain gas at this temperature as they have no force of attraction.
http://en.wikipedia.org/wiki/Absolute_zero