Return to Player
94.38%
Minimum bet
0.01
Game category
Video Slots
Volatility
Medium
Reels
6
Progressive jackpot
Yes
Popularity
Maximum bet
3000
Game Provider
Ainsworth
Bonus features
Yes
Paylines
30
Theme
Adventure
Play the Big Thunder slot online
In this Casino Ideal review, Evan Carrington describes Big Thunder as a well-designed 3D video slot in Ainsworth’s King Strike series. It is aimed at players looking for action-driven play and flexible betting, with free spins featuring multipliers and retriggers, stacked wilds, sizeable scatter multipliers and 4 jackpots. Because the game has a 6th bonus reel, a jackpot can trigger on any spin.
Theme and Story
Big Thunder is part of Ainsworth’s ‘King Strike’ slot series. Its setting is a dense South East Asian jungle, where tigers and gorillas appear alongside Buddhist and Hindu relics. The imagery presents these objects as symbols of luck and fortune woven into the reels.
Graphics, sound and animation
Ainsworth sets the game against a jungle backdrop filled with ancient relics and wildlife. The symbols feature detailed 3D artwork designed to stay clear on mobile and desktop screens alike. The design is presented as well suited to either device, with a chance to play for the progressive jackpot.
The sound also departs from the provider’s usual style. Ainsworth often relies on classic slot sounds, letting the action carry the experience. In Big Thunder, the online slot game adds tiger and gorilla roars, plus thunder as an animated bolt strikes the reels before a possible scatter bonus.
Top casinos to play Big Thunder:
How to play
The opening screen displays several elements at once. The Major, Maxi, Minor and Mini progressive jackpots sit above the 5-reel layout. A ‘Bonus Bet’ control appears on the right; it works as a 6th reel and, according to its description, adds no extra cost to a spin.
To play for a jackpot, select a wager per line and the number of lines using the menu or game interface. The line wager is multiplied by the chosen number of lines to calculate the total stake per spin. Once the amount is set, spins can be started one at a time or with auto spins.
Reels 3, 4 and 5 can show the rare gorilla, which acts as the wild. It substitutes for any regular symbol to help create or extend a winning combination. Gorilla wilds may land in stacks of 3 or as single symbols.
Regular symbols include an ancient religious mask, snake, shield, waterfalls, drums and the card ranks Ace, King, Queen, Jack, 10 and 9. The gorilla is also the highest-paying symbol: combinations pay 2,000x, 300x, 100x or 5x the bet per line when 5, 4, 3 or hit an active pay line. Other regular symbols form winning combinations with 5, 4 or 3 matching symbols.
A scatter symbol awards multipliers on the total spin bet and can trigger the free spins feature, which the review identifies as a source of many larger wins. The bonus reel’s ‘Kings Crown’ symbol is also required alongside the pictured regular symbols to award a progressive jackpot.
Jackpots and free spins
Each jackpot requires a specified combination to land on a pay line. In every case, the ‘crown’ must also land on the ‘Bonus Bet’ reel to activate the payout.
Major: 5 waterfalls, drums, shields, snakes or masks, plus the Crown on the bonus reel.
Maxi: 5 A, K, Q, J, 10 or 9 symbols, plus the Crown on the bonus reel.
Minor: 5 waterfalls, drums, shields, snakes or masks with the wild symbol, plus the Crown on the bonus reel.
Mini: A, K, Q, J, 10 or 9 with the wild symbol, plus the Crown on the bonus reel.
Landing the ‘Big Thunder’ logo scatter anywhere across the reels can trigger free spins. The scatter first awards a multiplier of the spin bet based on the number displayed. The listed values are 100x, 50x, 20x or 2x for 5, 4 or 3 scatters respectively.
The feature then awards 15 free spins on specially designed reels, with an added bonus reel displaying x3 and x5 multipliers. Wins are multiplied by the symbol on that bonus reel. The Gorilla remains a substitute, while scatters can award a spin-bet multiplier and retrigger 5 free spins.
Bet sizes, RTP and variance
The review describes a broad selection of bet settings for Big Thunder. The maximum is 30 lines at 100.00 per line, for a stated total of 3,000.00 per spin. The minimum is 1 line at 0.01 per spin. The listed RTP is 94.38%, and the game is classified as medium variance.
Review Summary
Big Thunder may suit players who enjoy free spins with multipliers and the possibility of a jackpot. The review highlights its jungle theme, graphics and animation, and how these elements work with the game’s features. It characterizes the overall play as lively, with several mechanics to explore.
Evan Carrington brings more than 12 years of experience in the iGaming industry, with a focus on reviewing online casinos, assessing slot games and examining player safety. Their work covers casino licensing, RTP, volatility, bonus terms and withdrawal policies. Drawing on practical testing and independent research, Evan provides clear, evidence-based reviews to help players understand gambling platforms, their features and possible risks.
