They have free satoshis that you can get from the box at the upper portion of the site. Is that not enough to use to test their games? Or you need huge play money to feel the game?
Betfury decreased the daily profit of faucet (free box) from 1800 sats to 720 sats per day. Maybe it's still enough to test some games like Dice, Plinko but I guess it isn't enough for slots. IIRC minimum bets are 0.001 mBTC per line for some slots games.
They decreased their free faucet from 25 satoshis/20 min to 10 sats/20 min due to abuse. Just accumulate them and you will be able to play some slots. Minimun bet on some slots is 0.01$ (most slots of Bgaming have this possibility) .