Yes this is 100% true
You can play your chromcast without any wi fi hotspot networks ;run HD video, 3D games, mp3, Internet many more (approximate 99.99%)
First please follow these simple steps :-
1 . install chromcast app in 2 android device (smartphone etc. )
2. Make device 1 as a hot spot with password (but first time Internet required )
3 . open chromcast app in 2nd device
4.its taken several minutes
5 . after making all set up
6.cast your big screen
7.but there is processing and playing speed is too slow
8. Then now is action time✌✌✌✌disconnect your 1st android device; and open chromcast app in 1st device, connect -- and-- cast your screen without Internet and wifi,it's running smoothly and all in HD Quality.
Not:------- mostly smartphone have """""Screen Mirroring """"" software; if this software specification is not available in your smartphone, please try to get it.
I am using this time samsung galaxy s4 GT i9500.