Big Thunder Slot Machine

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Big Thunder demo
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Return to player Min bet size Game type Variance Reels Progressive Jackpot
94.38% 0.01 Video Slots Medium 6 Yes
Popularity Max bet size Game provider Bonus Features Paylines Theme
3000 Ainsworth Yes 30 Adventure

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Big Thunder online slot game

The Big Thunder video slot title is a well-designed 3D slot from Ainsworth King Strike series. If you are looking for action-packed gameplay with flexible betting options, then this slot may be the answer as it rolls in free spins with multipliers as well as retriggers, stacked wilds, large scatter multipliers, and 4 jackpots that can be triggered at any time thanks to a 6th bonus reel.

Theme and Story Line

The Big Thunder slot title comes from the line of Ainsworth ‘King Strike’ series of slots. The theme is set in the dense jungles somewhere in South East Asia where tigers and gorillas roam amongst Buddhist and Hindi relics in a bid to bring good luck and fortune to the reels. 

Graphics, Sounds and Animations

Ainsworth’s slot developers have done an amazing job on this slot’s design. The graphic design work is centred on the jungle backdrop, and symbols of ancient relics and wildlife, which are all in 3D with a crisp finish so they appear clearly on mobile and desktop devices. Regardless of the device, you play this slot on, you will be able to have a shot at the progressive jackpot on a quality designed slot. 

The sound effects are also different compared to most Ainsworth games. Usually, this slot developer goes for classic slot sounds and lets the gameplay do all the talking. However, on the Big Thunder online slot game you are treated to tigers and gorillas roaring, the sound of thunder as an animated thunderbolt hits the reels in anticipation of triggering the bonus scatter.


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When you initially open the slot, there is a lot to take in as there is so much going on. At the top of the 5-reels, you have the Major, Maxi, Minor, and Mini progressive jackpots. On the right-hand side, there is the ‘Bonus Bet’ option, which is effectively the 6th reel and it costs you nothing extra to play this reel. 

To take a shot at the jackpot you will need to set you your bet per line and line bets. You can do this via the menu or slot interface. You bet per line is multiplied by the number of lines you wager to tot up your total bet per spin. After getting your spin bet amount ready you can spin manually or set auto spins.

Reel 3, 4, and 5 are home to the rare gorilla species, which is the wild card symbol. The Gorilla symbol can act as any of the other regular symbols helping you to complete and extend combination payouts. Some wild Gorilla symbols are stacked in sets of 3 and some are lone symbols. 

Regular symbols that can link up with the wild include the ancient religious mask, snake, shield, waterfalls, drums, Ace, King, Queen, Jack, 10, and 9 symbols. The wild symbol is also the highest paying combination paying 2,000x, 300x, 100x, or 5x multipliers applied to your bet per line when 5, 4, 3 or hit an active pay line. All other regular symbols pay for combinations with 5, 4, or 3 symbols. 

There is also a scatter symbol that pays out multipliers of your total spin bet, and this triggers the free spins game, which is where most of your big wins will come from. And obviously, you will be vying for the bonus reel ‘Kings Crown’ symbol to line up with the pictured regular symbols to release the progressive jackpot win. 

Big Thunder 1

Bonuses and Free Spins

Winning one of the jackpots requires particular combinations to come in on a pay line. In all cases, you will need to have landed the ‘crown’ symbol on the ‘Bonus Bet’ reel to activate a jackpot payout. 

Major: a 5-symbol combination of either waterfall, drum, shield, snake, or mask Crown on bonus reel.

Maxi: a 5-symbol combination of either A, K, Q, J, 10, or 9 symbols Crown on bonus reel.

Minor: 5 waterfalls, drums, shields, snakes, or masks with the wild symbol Crown on bonus reel.

Mini: A, K, Q, J, 10, or 9 with the wild symbol Crown on bonus reel.

Aside from vying for the possibility of landing one of the jackpots, there is also the free spins game that is triggered by landing the ‘Big Thunder’ logo scatter symbol across the reels in any position. You will firstly be paid out a spin bet multiplier depending on how many scatter symbols landed on the reels. This will be 100x, 50x, 20x, or 2x for 5, 4, or 3 scatters respectively. 

Next up you have 15 free spins on custom free spins reels with an added bonus reel that contain x3 and x5 multiplier symbols. Any wins on the reels will be multiplied by the multiplier symbol on the bonus reel. The Gorilla will still be a substitute symbol and scatters can still pay spin bet multiplier plus retrigger 5 free spins. 

Big Thunder 2

Bet sizes, RTP and Variance

You can pretty much set your bet to almost anything you please on the Big Thunder slot title. The highest bet settings will be 30 lines at 100.00 per line, which gives you a max bet of 3,000.00 per spin. The lowest bet is 1 line at 0.01 per spin making this ideal for penny slot players. Your expected RTP on your bets is 94.38% and this is a medium variance slot game. 


If you like free spins games with multipliers while always being in with the chance of landing a killer jackpot payout, then Big Thunder will suit you down to the ground. Most people will easily get on with the theme and the graphics as well as some of the animations. Everything seems to just work well together giving this slot great features, exciting gameplay, and overall it just has a nice vibe to it. 

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