Cardboard

A kid's fantasy
It can be anything a kid can imagine
A castle, dragon, fort, city
Even a nightmare
A playground of imagination
Water can be its fate
Armour to be worn
Struck by a sword
A game to be made
Pirates vs. aliens
Canons to be shot
Lasers to be beamed
At the end of the day
You put it away
'Til the next time you play.