Thunder Coins XXL: Booster Cells

Thunder Coins XXL: Booster Cells Slot Review

A gold-rimmed thunderbolt medallion presides over an electric-storm void, a white-hot lightning fork branching down the right of the screen and a heaped drift of gold coins spilling across the bottom-left corner. It’s a Playson build on a 3×5 grid with 15 fixed paylines, and its best idea is right there in the title: coins that stay where they land and grow.

Four jackpot ribbons sit stacked along the top of the reel frame, one for each tier. The game publishes no RTP, and there’s no stated maximum win either, so the ceiling is whatever the coins and jackpots build. Where Clover Smash went for smashing multipliers, this one banks its value in place and lets the storm build on it.

Base Game & Features

The base game runs on those 15 fixed lines, awarding wins for consecutive symbols from left to right. Only the highest win per line is paid. That’s the whole payline mechanic, and it’s a conventional one.

The interesting part is what the coins do before they pay. Thunder Coins XXL: Booster Cells stores coin values on the reels rather than clearing them away, and that storage is the engine of everything else.

Thunder Coin

The Thunder Coin is a lightning-bolt symbol that only lands on reel 2. On its own it’s a trigger; paired with any Coin, it sets off the Thunder Feature. That single-reel restriction matters more than it sounds, because everything the game pays flows through it.

Thunder Feature

Landing a Thunder Coin in combination with any Coin collects the values of all Coins on the screen, Jackpot Coins included, and adds them to the win for that spin in the Main Game or to the Total Win in the Bonus Game. In full, the feature works like this:

• Any Coin landing on a position that already holds a stored value adds the stored value to the Coin’s value, and the total becomes the new stored value for that position
• Positions can stack, so a busy reel keeps compounding
• Each Thunder Coin randomly boosts multiple stored values on the reels when it lands
• Collected values are added to the current spin’s win in the Main Game, or to the Total Win in the Bonus Game
• Once respins run out, the Bonus Game ends and every Thunder Coin value is added to the Total Win

The Main Game and Bonus Game versions of the collection differ only in where the money goes. In the Main Game, the sweep lands on that spin’s win and play carries on as before. In the Bonus Game, everything feeds a running Total Win that keeps growing until the respins expire.

It’s a mechanic that rewards patience with the grid: the longer values sit stored, the more a single Thunder Coin collects. The flip side is that a string of spins without one leaves all that banked value doing nothing.

Jackpot Coins

Jackpot Coins sit apart from the ordinary Coin symbols. When one lands, it feeds the jackpot ribbons stacked along the top of the reel frame, and the Thunder Feature collects their values along with everything else. There are four ribbons, one per tier:

• Red ribbon
• Green ribbon
• Blue ribbon
• Purple ribbon

Thunder Coins XXL: Booster Cells Bonus Game

The Bonus Game is where the stored-value system pays off properly. Coins lock in place, values accumulate per position, and the Thunder Coin sweeps through collecting and boosting as it goes. Jackpot Coins feed the ribbons along the top of the frame.

Respins drive the round, and the flow runs in a fixed order:

• A Coin lands and locks its value into its position
• If that position already held a stored value, the two amounts merge into one bigger stored value
• Any Thunder Coin boosts multiple stored values at random
• The respin count resets while new Coins keep arriving
• When the respins run out, every Thunder Coin value is swept into the Total Win and the round closes

Demo play showed the Thunder Coin arriving on reel 2 again and again, with the win figure climbing as the round went on before fading out. The sequence of displayed wins ran:

• 0.50 – the round’s first collection
• 6.00 – steady build as stored values accumulate
• 17.00 – a stored coin value of 17.00 showing beside the Thunder Coin
• 21.00 – the peak of the run
• 1.00 – a quiet close

That arc is the shape of the game: a slow build that pays out in one collected sweep, with the biggest numbers arriving only after the grid has had time to fill.

Bonus Buy and Bet Boosters

There’s a BONUS button in the left-hand panel for buying direct entry into the round. Alongside it sit two optional bet boosters, each a standing extra bet rather than a one-off purchase:

• Double Chance – doubles the chance of triggering the Bonus Game for 1.5x the total bet
• Thunder Spin – triples the trigger chance and guarantees one Thunder Coin every spin, for 4x the total bet

Thunder Spin is the more interesting of the two. A guaranteed Thunder Coin each spin means the collection feature runs constantly rather than waiting for reel 2 to cooperate, though at four times the stake it’s a genuine commitment rather than a casual toggle.

Double Chance is the lighter option, a smaller premium for a doubled trigger rate. Neither booster changes what the round pays once it starts; they only change how often you get there, and how much each spin costs on the way.

Our Honest Verdict

Overall Rating: 7.1/10

Thunder Coins XXL: Booster Cells is a coin-collector built around one idea, and it commits to it. Values don’t pay and vanish; they sit on the grid, stack when new coins land on them, and get collected in a sweep when the Thunder Coin arrives. The base game can feel like a holding pattern between collections, but that’s the design, and the build during a bonus round, values compounding position by position, is the reason to be here.

Its strength is the booster system. Thunder Spin, at 4x the bet, turns the collection mechanic from an occasional event into the whole game, and the demo runs showed exactly the climbing arc it’s built for. The weakness is the spec silence: with no published RTP, anyone playing is taking the maths on faith, and the storm-and-gold presentation is doing a lot of the persuading.

This suits players who like a long build and don’t need a stated ceiling to aim at. Anyone who wants the numbers up front should look elsewhere in the Playson coin family. For the rest, the storm is well worth standing in.

Thunder Coins XXL: Booster Cells FAQs

• How many paylines does Thunder Coins XXL: Booster Cells have?

  The game has 15 fixed paylines. Wins pay for consecutive symbols from left to right, and only the highest win per payline is awarded.
• What is the grid size of Thunder Coins XXL: Booster Cells?

  It’s a 3×5 grid: 3 reels with 5 rows visible on screen.
• How does the Thunder Feature work?

  Landing a Thunder Coin in combination with any Coin collects the values of all Coins on screen, including Jackpot Coins, and adds them to the current spin’s win or the Bonus Game Total Win. Any Thunder Coin that appears will also bump up several of the values already stored on the reels at random.
• Which reel does the Thunder Coin land on?

  The Thunder Coin only lands on reel 2. It’s the trigger for the Thunder Feature.
• What does Double Chance cost?

  Double Chance doubles the chance of triggering the Bonus Game and costs 1.5x your total bet.
• What does Thunder Spin do?

  Thunder Spin triples the chance of triggering the Bonus Game and guarantees one Thunder Coin on every spin. It costs 4x the total bet.
• Can you buy the bonus on Thunder Coins XXL: Booster Cells?

  Yes, there’s a BONUS button in the left-hand panel that takes you straight into the Bonus Game.
• When is Thunder Coins XXL: Booster Cells released?

  Thunder Coins XXL: Booster Cells’ release date is 17 September 2026. It’s made by Playson.