I don't believe that this offer is doable at all without paying at least a few dollars. The time limit is 20 days and it says to get to level 40. Seems easy enough, right? 40 isn't that big of a level compared to the level 70/100/200 we're used to seeing.
Well, not really. In fact, I'd argue it's much worse than Huuuge or Billionaire casino, because they give you 2x coupons for exp.
Despite me playing every single day, whilst heavily babysitting the app, and even investing $15 to finish the offer, I struggle to even level up once a day. Jackpots are a help but ones that actually get you anywhere or are 'big wins' are so far and few in-between. I've only won one major jackpot through one of the bonus games, (I was around 100m-200m coins) and while it helped, it did not get me much closer to my goal. Betting the minimum spin still drains my coins. I claim the FB coins and the daily login coins every day.
It's hard to maintain your chips and levelling up is even worse (0.03% at a 440k bet, which is hard to maintain since chips drain fast, even if you're playing at less than 1% of your total balance). The bonus game is VERY inconsistent. At first I assumed it'd be triggered when the coin bowl at the top filled, but no. Sometimes it'll require another 50+ spins for it to trigger, and if you change your bet, you will have a much smaller earn even if you were betting 2m+ per spin.
I still have not finished the app after 10 days of consistent and daily playing. I'm at level 35 finally, but I'm not even sure if I'll be able to pull through without another purchase (which I really don't want to do). Overall, you are way better of going for something like Pop Slots (which is super do-able) or Huuuge Casino. End of rant.