Nitropolis 4 is a 6 column, 4 rows slot with spinning reels and dropping symbols. The columns can expand upwards to a maximum of 8 rows.
The minimum bet is € 0.20, and the maximum bet is € 50.00. Each bet is 100 coins.
Wins begin with the leftmost reel and pay left to right only on consecutive reels. In case of Both Ways the wins can also begin with the rightmost reel and pay right to left only on consecutive reels. Only the highest win per active payline is paid out.
Winnings and winning combinations are paid out according to the Paytable.
A game round starts on the selected bet level when the player hits the Spin button.
The game can be played automatically by activating Auto Spin. Hold down the Spin button or use the Auto Spin button to set the number of game rounds to be played automatically.
Winnings are presented in the player's currency or in coins. The player can change preference in Settings.
Nitropolis 4 is played in two modes; normal mode and bonus mode with free spins.
All spins in normal mode start with 4 rows and 4,096 ways to win.
A Nitro Reel always covers two symbol positions and contains 4, 6, 8, 10 or 12 identical 1x1 payout symbols. A big Nitro Reel always covers six symbol positions and contains 2, 3, 4, 5 or 6 identical 2x2 payout symbols.
A Nitro Reel can contain a super bonus symbol and is then only counted as one 1x1 symbol regardless of the size indicator of the Nitro Reel. The number of ways to win resets to the previous number when the super
bonus symbol spins out.
The wild symbol and all low, mid and high value symbols exist in three sizes; standard 1x1, Super 2x2 and Mega 3x3. All big symbols are counted as consisting of the number of 1x1 symbol instances it covers, e.g. a Super 2x2 consists of 4 standard 1x1 symbols.
Empty spaces occurring below big symbols and below big Nitro Reels are filled with 1x1 sized symbols of the same type as the big symbol.
The wild symbol substitutes for any symbol except the bonus and the super bonus symbols. A payline of all wilds pays as the highest value symbol.
A Nitro Multiplier is a blocker that can appear in a Nitro Reel, and holds a value of x4, x6, x8, x10 or x12. It multiplies all wins in view and is multiplicative in case there are several Nitro Multipliers in view.
The Nitro Multiplier is only counted as one 1x1 symbol regardless of the size indicator of the Nitro Reel. The number of ways to win resets to the previous number when the Nitro Multiplier symbol spins out.
All wins in the current symbol spin/drop are collected and thereafter all symbols which were part of a winning combination explode except for the Nitro Reels. The remaining symbols fall vertically until they reach a resting position, an additional row is added at the top and new symbols drop in to fill the empty spaces. The Avalanche feature continues as long as new winning combinations appear.
Nitro Reels and Nitro Multipliers that are part of a winning combination are kept and respin during the symbol refill.
Each additional symbol drop will add an additional row of symbols, up to a maximum of 8 rows, increasing the number of ways to win. The number of ways to win increases as the number of rows increases. The number of ways to win also increases as the number of Nitro Reels and the quantity of symbols inside the Nitro Reels increase.
The Nitro Booster consists of two screens which may award features prior to the main reels stop, when the Nitro Booster moves upwards and
in conjunction with a win when the reels are fully expanded. There are 8 features; 5 affect the main reels and 3 affect the Nitro Reels.
The Nitro Booster features affecting the main reels are: Both Ways, Redrop, Max Rows, Garbage Collect and Nitro Appear.
The Nitro Booster features affecting the Nitro Reels are: Nitro Wild, Nitro Upgrade and Nitro Match.
The Redrop feature is activated when there are no more wins. Bonus symbols, wild symbols, Nitro Multiplier and Nitro Reels remain during the Redrop. The Nitro Reels respin and new symbols drop in from above to fill up the current active number of rows. Only 1 Redrop feature can trigger at a time.
The Both Ways feature activates when it lands. Subsequently all ways connections then pay from left to right starting from the leftmost reel, and from right to left starting from the rightmost reel. The Both Ways feature remains active throughout the Avalanche cycle in normal mode. The Both Ways feature remains active for the remaining free spins when activated in bonus mode. Only 1 Both Ways feature can be triggered in normal mode and bonus mode respectively.
The Max Rows feature activates when it lands, expanding the reels up to maximum 8 rows. Only 1 Max Rows feature can be triggered in normal mode and bonus mode respectively.
The Garbage Collect feature randomly selects one symbol and removes all instances of it from view prior to gravity and symbol refill. Nitro Reels that contained the selected symbol will respin.
The Nitro Appear feature randomly places a Nitro Reel or a big Nitro Reel of any size during the ongoing spin. The Nitro Reel replaces the existing symbols on the selected positions.
The Nitro Wild feature randomly selects an existing Nitro Reel in view and fills it with wild symbols. In case there are no Nitro Reels currently in view, the feature will be kept pending in the Nitro Booster until either a Nitro Reel appears or the game round ends.
The Nitro Upgrade feature randomly selects an existing Nitro Reel in view and increases its ways value. Upgrading Nitro Reels with symbols increase the number of symbols within the Nitro Reel. Upgrading Nitro Reels with a multiplier increases the multiplier value within the Nitro Reel. In case there are no Nitro Reels currently in view, the feature will be kept pending in the Nitro Booster until either a Nitro Reel appears or the game round ends.
The Nitro Match feature is activated when the reels stop, or when the symbol refill is complete. It randomly selects an existing Nitro Reel in view and matches it with another symbol in view to create a win. If no winning match is possible the selected Nitro Reel will be matched with an adjacent Nitro Reel. If that is not possible either it will be matched with the highest value symbol on the adjacent reel(s). In case there are no Nitro Reels currently in view, the feature will be kept pending in the Nitro Booster until either a Nitro Reel appears or the game round ends.
A combination of three or more bonus symbols during normal mode triggers the bonus mode with free spins. The Super Bonus Game will be triggered in case at least one of the bonus symbols is a super bonus symbol.
- bonus symbols: 8 free spins
- bonus symbols: 12 free spins
- bonus symbols: 16 free spins
- bonus symbols: 20 free spins
Super bonus symbols can only appear in a Nitro Reel. A super bonus symbol will only be counted as one no matter the Nitro Reel's size indicator. The number of ways to win resets to the previous number when the super bonus symbol spins out.
The Both Ways and Max Rows features become deactivated in case they are active when Bonus mode is triggered.
The free spins bonus game always starts with the safety level set to 4 rows. Every winning free spin advances the safety level one row. Nitro Reels and Big Nitro Reels may advance the safety level several rows at
once if they are stacked above the level that a regular win provides.
The advancement of the safety level occurs after the payout. The next free spin starts from the new safety level. The safety level can at most advance 4 rows resulting in a total of 8 rows.
During free spins, all Nitro Reels are kept and remain in play for the remaining free spins.
The Super Bonus game is played with Max Rows and Both Ways activated.
Three or more bonus symbols during bonus mode award additional free spins. The number of additional free spins is determined in the same way as when initially triggering the bonus game. The Super Bonus Game is triggered in case at least one of the bonus symbols is a super bonus symbol.
The free spins bonus game ends when no free spins remain or when the maximum win has been reached.
Winnings are paid out at the end of the bonus mode.
No bets can be changed during an ongoing game round. A game round ends if the maximum win is reached.
The theoretical payout (RTP) in Nitropolis 4 is 94.0%.
The game has a maximum win of 50 000x the placed bet. In the event of malfunction all bets and wins are void.
The X-iter feature offers several different game modes.
Super Bonus: Guarantees a game round with entry to the super bonus game at the cost of 500x the selected bet. All free spins are played with Max Rows and Both Ways activated.
Bonus: Guarantees a game round with entry to the bonus game at the cost of 100x the selected bet.
Super Spin: 1 spin which is played with Max Rows and Both Ways activated at the cost of 25x the selected bet.
Nitro Booster: 1 spin where the Nitro Booster always provides 2 features when activated at the cost of 10x the selected bet.
Bonus Hunt: 1 spin with more than double the chance to trigger the bonus game at the cost of 2x the selected bet.
The X-iter features can only be activated in the base game.
The minimum X-iter cost is € 0.40, and the maximum cost is € 25,000.00.
The theoretical payout (RTP) for all X-iter game modes in Nitropolis 4 is 94.0%.
All game rules apply for the X-iter features as well.
Last modification date: 2/24/2023