Nitropolis 4 takes the animal gangs to an offshore oil rig. Vacation's over. Time to drill for Nitro. ELK Studios keeps the series going with expanding reels, Nitro Reels, multipliers that multiply each other, and 8 different features that can trigger randomly.
I've followed the Nitropolis series since the start. Each game adds more chaos. Part 4 doesn't change things up completely but it refines what worked before. Same animal world. Same heavy soundtrack. Same potential for the grid to go crazy with ways to win.
Here's what I found.
| Provider | ELK Studios |
| Release Date | 2023 |
| Grid | 6 reels, 4 to 8 rows (expands) |
| Ways to Win | 4,096 base (up to 262,144 at max rows) |
| RTP | ~94% (can vary by casino) |
| Volatility | High |
| Max Win | 50,000x |
| Min/Max Bet | €0.20 to €50 |
| Bonus Buy | Yes (X-iter from 2x to 500x) |
RTP Warning: The RTP is around 94%. That's below average. Check what version your casino runs before playing.
Nitropolis 4 vs Nitropolis 5
Wondering which Nitropolis to play? Here's how they compare.
| Feature | Nitropolis 4 | Nitropolis 5 |
|---|---|---|
| Release | 2023 | 2024 |
| Theme | Offshore oil rig | Final battle vs Sgt Nitro Wolf |
| Grid | 6 reels, 4 to 8 rows | 6 reels, 4 to 8 rows |
| Max Ways | 262,144 | 4,096 (expanding via features) |
| RTP | ~94% | ~94% |
| Volatility | High | Very High |
| Max Win | 50,000x | 50,000x |
| Nitro Booster Features | 8 features | 11 features |
| Unique Feature | Safety level system | NPD Holding Cells, Boss Battle |
| Super Bonus | Max Rows + Both Ways | Max Rows + Both Ways + NPD Holding Cells |
| X-iter Options | 5 (2x to 500x) | 5 (3x to 500x) |
| Best For | Players who like safety level mechanics | Players who want more features and Boss Battle |
Quick take: Both games share the same max win and RTP. Nitropolis 5 adds more features including a Boss Battle where you fight the main villain. Nitropolis 4 has the safety level system that builds rows during free spins. Pick based on whether you want more features (Part 5) or the row building mechanic (Part 4).
How It Looks
Offshore oil rig setting. The animal gangs are drilling for Nitro instead of racing around the city. Machinery everywhere. Dark skies. Gritty feel.
The audio is heavy. Industrial beats and bleeps. ELK knows how to build atmosphere in these games.
Two Nitro Booster displays sit above the reels. When they trigger, features drop onto the grid. It fits the drilling theme.
Base Game
You start with 6 reels and 4 rows. That's 4,096 ways to win. Wins normally pay left to right. When Both Ways activates, they pay right to left too.
Symbols:
- Low pays: J, Q, K, A (0.3x for six of a kind)
- Mid pays: Four gang logos (0.8x to 1x for six of a kind)
- High pays: Four character symbols (1.25x to 3x for six of a kind)
- Wild: Spiky mine tile, fills in for all pay symbols
You need at least three matching symbols to win.
Avalanches
Every win removes those symbols. New ones drop in. An extra row gets added at the top. This keeps going until no new wins form.
The grid can grow from 4 rows to 8 rows. At max height you have 262,144 ways to win. That's a lot of ways for wins to form.
Big Symbols
Super symbols (2x2) and Mega symbols (3x3) can show up on any spin. Any pay symbol or wild can land as a big symbol.
When a 3x3 premium lands on an expanded grid, wins add up fast.
Nitro Reels
These take up two spots on the grid and can land on any reel.
What they hold:
- Regular Nitro Reels: 4, 6, 8, 10, or 12 normal sized payout symbols
- Big Nitro Reels: Cover six spots and hold 2, 3, 4, 5, or 6 big payout symbols
Nitro Reels flood the grid with matching symbols. On an expanded grid with multiple Nitro Reels, the ways to win get crazy.
Nitro Multiplier
Nitro Multipliers also cover two spots but count as one symbol. They multiply all wins you can see.
Values: 4x, 6x, 8x, 10x, or 12x
The key part: When more than one Nitro Multiplier is on screen, they multiply each other. Two 6x multipliers becomes 36x. That's where the big wins come from.
Nitro Booster
Two displays above the grid can trigger 8 different features at random.
The 8 effects:
- Redrop: No wins left? Bonus symbols and Nitro Reels stay while everything else gets replaced
- Both Ways: Wins pay in both directions
- Garbage Collect: Random symbols removed, causing an avalanche
- Max Rows: Grid expands to full 8 rows
- Nitro Appear: Random Nitro Reel placed on the board
- Nitro Wild: A Nitro Reel fills with wilds
- Nitro Upgrade: A Nitro Reel's value goes up
- Nitro Match: A Nitro Reel matches another symbol to create a win
These can trigger any time. Multiple features stacking together is where things get wild.
Bonus Game
Land 3, 4, 5, or 6 bonus symbols to trigger free spins.
| Bonus Symbols | Free Spins |
|---|---|
| 3 | 8 |
| 4 | 12 |
| 5 | 16 |
| 6 | 20 |
During free spins:
- All Nitro Reels become sticky until the feature ends
- Each win raises the safety level by one row
- The next free spin fills the grid to your current safety level (max 8 rows)
- You can retrigger more spins
Sticky Nitro Reels plus growing rows means the grid fills up with ways to win as you play through the feature.
Super Bonus Game
If one of your bonus symbols is a Super Bonus symbol, you get the Super Bonus instead.
Super Bonus gives you:
- Max Rows active the whole time (8 rows throughout)
- Both Ways active the whole time (wins pay both directions)
- Sticky Nitro Reels
This is the good stuff. 262,144 ways paying both directions with sticky Nitro Reels building up. The 50,000x max win happens here.
X-iter Bonus Buy
ELK's X-iter system gives you 5 options.
| Option | Cost | What You Get |
|---|---|---|
| Bonus Hunt | 2x | More than double the chance to trigger bonus |
| Nitro Booster | 10x | Two features from the Nitro Booster |
| Super Spin | 25x | Max Rows and Both Ways active |
| Bonus | 100x | Straight into the bonus game |
| Super Bonus | 500x | Super Bonus with Max Rows and Both Ways |
The 2x Bonus Hunt is cheap for longer sessions. The 10x Nitro Booster lets you try features without going all in. The 500x Super Bonus is pricey but gives the full experience.
If you like bonus buy slots, there's a good range here.
Bankroll Advice
High volatility with 50,000x max win. The 94% RTP is low.
Bring at least 300 to 400x your bet. At €1 spins, that's €300 to €400. Base game can have dry stretches. The real money comes from bonus features with sticky Nitro Reels and multipliers stacking together.
The 500x Super Bonus buy needs a bankroll that can handle losing it.
Mobile
Works fine on mobile. The expanding grid fits the screen. Lots happening visually but it stays playable. Audio sounds great with headphones.
Who Should Play This
Nitropolis 4 works for you if:
- You liked earlier Nitropolis games
- Avalanche mechanics appeal to you
- You want multipliers that multiply each other
- 262,144 ways at max rows sounds fun
- Random features triggering excites you
- 50,000x max win potential is enough
Skip this if:
- 94% RTP is too low
- You want simpler gameplay
- The visual chaos feels like too much
- High volatility is too risky
- You prefer fewer mechanics
What I Liked
- 50,000x max win potential
- Nitro Multipliers multiply each other
- 8 different Nitro Booster features add variety
- Sticky Nitro Reels during bonus build up nicely
- Super Bonus with Max Rows and Both Ways hits hard
- X-iter has options from 2x to 500x
- Great atmosphere and audio
What I Didn't Like
- 94% RTP is below average
- Base game can drag between features
- Lots of mechanics to keep track of
- Super Bonus is rare without buying
- 500x buy is expensive
My Rating: 3.5/5
Good multiplier system, solid max win, fun feature variety. The 94% RTP and complex mechanics keep it from scoring higher. Best for Nitropolis fans who don't mind lower returns for bigger win potential.