My kids still talk about the cardboard outdoor fort I'd made like 3 yrs. ago...But this raises the bar several feet.
The special effects here are off the hook!
This though is NOT work safe and is not for those with gentile sensibilities due to;
Depiction of gore, simulated blood, gratuitous violence, grenades blowing ish up, negative display of firearms facsimile use...And overall significant butt kickage by use of assault cardboard.
YouTube - Cardboard Warfare