Millionaire Mystery Box


Millionaire Mystery Box Slot Review

Millionaire Mystery Box is a video slot from Big Time Gaming with 5 reels and 243 ways to win. Released in October 2019, this game can be played at online casinos such as Rizk, Unibet or Casumo.

Theme and general information

Millionaire Mystery Box is based on Who Wants to be a Millionaire, another release from Big Time Gaming, already a few years old now. We get the typical setup of the studio in the background and the soundtrack is also emulating that of the game show. It’s nothing spectacular but still kind of cool, especially for fans of the game show.

The hot seat is visible, the studio fairly dark. There are some neon highlights here and there. The reels itself are ruled by high value gems and low value card symbols. It all looks quite rich, though, and even though the reel symbols have nothing to do with the game show at all, they still somehow fit into the setup.

The purple gem pays out 25 coins for 5 on a payline. The red gem is worth 3 coins for such a win. The green and blue gems pay 2 and 2.5 coins, respectively. The low value card symbols range from 9 to A.

You can play this game from 0.10 to 40.00 per spin, which makes it suitable for the budget conscious.

Mystery symbols and multiplier wilds

In the base game, we’re particularly interested in the mystery box and multiplier wilds. The latter come attached with a 2x multiplier as a standard. They only land on reels 2, 3 and 4, however. Better still, though, they multiply with each other should more than one be part of a winning combination.

The mystery box is simply a symbol with a question mark on it. When it lands, also only on reels 2, 3 and 4, it will reveal another of the reel symbols, often in order to create a win. They mystery box can also transform into a wild or a scatter.

Free spins with climbing multipliers

The highlight are, of course, the free spins. This is where the game comes into its own and most closely resembles the original Who Wants to be a Millionaire setup. You need 3 or more scatters to get 7 free spins. On the left-hand side you’ll find the ladder arrangement that reminds us of the ladder you can climb in the game show.

Each scatter you receive during the free spins, will move you up one step on the ladder. This is what you get:

  • 1 scatter = 3x multiplier +1 spin
  • 2 scatters = 4x multiplier +1 spin
  • 3 scatters = 5x multiplier +3 spins
  • 4 scatters = 6x multiplier +1 spin
  • 5 scatters = 7x multiplier +1 spin
  • 6 scatters = 8x multiplier +1 spin
  • 7 scatters = 9x multiplier +3 spins
  • 8 scatters = 12x multiplier +1 spin
  • 9 scatters = 15x multiplier +1 spin
  • 10 scatters = 30x multiplier +1 spin
  • 11 scatters = 50x multiplier +3 spin

With the maximum multiplier it’s possible to win up to 12,000x your stake.

Conclusion: A simple but entertaining slot with huge potential

The theoretical RTP (Return to Player) of Millionaire Mystery Box is 96.64%, which is excellent especially for a medium variance slot such as this one.

This game may not be the most innovative or exciting slot out there, but the gameplay is solid, and the mechanics work quite well. When you do manage to climb the ladder a few steps in the free spins, even the excitement manages to climb.

Plus, with the excellent RTP and the high maximum payout, you may just end up a little closer to becoming a millionaire as well.


Mobile Free spins
Yes Yes
Lines Bonusround
243 No
Reels Progressive
5 No
RTP Wild symbols
96.64% Yes
Min. Stake Autoplay
0.10 Yes
Max. Stake Multiplier
40 Yes
Volatility / Hit Frequency Scatters
Medium No
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Play Millionaire Mystery Box on the following casinos