Dr Zappo

Dr Zappo is a Hacksaw Gaming slot released on 29 September 2026, a comic-book laboratory comedy with a mad scientist in a white coat and purple hair and his assistant, Mr. Brain, a monkey with an exposed brain in a glass dome. The game is played on 5 reels with four rows and paylines, the volatility is rated 3 out of 5 and the maximum win is 10,000x the bet. Hacksaw lists four RTP versions: 96%, 94%, 92% and 86%.

A Cartoon Street And A Strange Experiment

The reels hang from a blue machine in a bright street scene, with a neon eye sign on the right and a character in a red suit on the left. The story, as the publisher tells it, is that the doctor and Mr. Brain have conducted a new experiment which produced a beast so ferocious that it can trample a whole city in minutes. The symbols continue the theme: a ray gun, a green bomb, a robot head, a creature in a jar and the clown-haired doctor are the pictures, with 10, J, Q, K and A drawn in comic lettering. The Wild is a purple W tile.

Eyeball Wilds

The main feature is the Wild Eyeball. EyeBall symbols land and then shoot in one of three directions: straight up, diagonally to the left or diagonally to the right. As they shoot, they transform the paying symbols on their way into Wilds. This makes every Eyeball a small chain reaction, and a spin with several of them can convert a large part of the grid.

Energy Fields

The second mechanic is the Energy Field. When an Eyeball shoots at an Energy Field, it bounces off and continues in another direction, transforming more symbols on its way. If the Eyeball hits an existing Wild or another Eyeball, it adds a multiplier value to that Wild symbol. Since the multipliers show on the Wilds as 2x, 5x, 6x and so on, the total of a winning line can grow a lot when a boosted Wild is part of it.

Three Bonus Games

The FS scatter symbols trigger the bonus games. Landing three or more at the same time starts one of the three bonuses, and each one gives 10 free spins:

• Eyeconic (3 FS): the free spins come with an increased chance of landing Eyeball symbols;
• No-Brainer (4 FS): each Eyeball symbol that activates shoots in two different directions in one spin, and extra FS symbols landing during the bonus award more free spins;
• It’s Electrifying (5 FS): a hidden epic bonus where at least one Eyeball lands on every free spin.

In the free spins the background moves from the street to the doctor’s underground lab, with green tubes and screens behind the grid, and a bar at the bottom shows the total win and the free spins left.

What The Screen Shows

During the free spins the Wild tiles are purple squares with a white W, and the multiplier tiles are square badges such as 5X, 6X and 2X, which sit next to the Wilds on the grid. Green bombs and robot heads are among the other symbols, and the low pays are the card letters in blue, pink and green. A typical bonus spin starts with a few Eyeballs, the first shots turn symbols into Wilds, and a win bubble in the middle of the grid shows the payout, for example 4.00 or 13.46 on a 2.00 bet in a bought No-Brainer round.

Because Eyeballs can multiply existing Wilds, a spin where several of them connect is the one that stands out from the rest.

The Buy Menu

The Buy Bonus button opens four options, here at a 2.00 stake:

• Bonushunt FeatureSpins at 3x: each spin is five times more likely to trigger a bonus game (medium volatility);
• Zigzag Zappo FeatureSpins at 100x: each spin guarantees at least two EyeBall symbols (high volatility);
• Eyeconic at 50x: 10 free spins with a bigger chance of Eyeballs (medium volatility);
• No-Brainer at 200x: 10 free spins with Eyeballs shooting in two directions (medium volatility).

After you confirm a purchase, the award screen shows the name of the bonus and the number of free spins before the round begins.

RTP, Volatility And Max Win

With four published RTP levels, from 96% down to 86%, Dr Zappo is a game where the rule screen is worth checking before you play for real money. The volatility is 3 out of 5, and the maximum win is 10,000x the bet. The bonuses with the most Eyeballs, and the multipliers that stick to the Wilds, are where the larger results come from.

Who Should Try It

Dr Zappo is for players who enjoy colourful, humorous slots with a visible “chain reaction” mechanic. Watching the eyeballs fire and bounce is entertaining, the buy menu is wide, and the three bonuses give the free spin hunt a clear ladder. It is also a good demo game to learn how Hacksaw’s FeatureSpins options differ from a normal Buy Bonus.

You can try this game on AztecParadise Online Casino. There’s a unique casino bonus offer of 300% up to £2000 for a limited time.