[ChrisA]

heres some ideas:
the pit area flooring at nats
something hard like concrete or wood that cant be 'dug' into
astroturf (heck why not)
dirt, gravel, or any other loose material (would have to be raked after each round but cool none the less)
water would be cool, but why not liquid nitrogen (jk but would be funny)
plastic sheeting (slick and hard to grip especially when waxed)
waxed floor
rubber mats (though these are easily torn)

i mostly would like to see the playing field more uneven (though can make it tough for teams to recreate (maybe make it a surprise surface for each regional, wouldnt that be fun)