Interview with Bart Crebolder on Why Bonus Features Matter So Much in Modern Slots

Modern slots rarely wait long before throwing something at the screen.

A reel expands. A multiplier drops. Symbols disappear. A meter fills up. Then a bonus round starts doing five things at once.

Some features genuinely make a slot more interesting. Others are just noise wrapped around the same old maths.

Today, we’re speaking with Bart Crebolder, the casino reviewer behind many of the insights from Online Casino Groups. He tests slots, bonus rounds, casino lobbies, and the terms players usually notice after spending money.

Why do bonus features matter more now than they did before?

I think players simply expect more from a slot now.

A plain five-reel game can still work, but it needs a very good reason. Maybe the pace feels great, or the theme carries it. Otherwise, three symbols landing on a line gets old quite quickly.

When we test newer slots at OnlineCasinoGroups, the bonus feature is usually where the game shows its real idea. The base game often spends most of its time building towards that moment.

Gates of Olympus is a clear example. Players remember the tumbles and multiplier drops, not the coloured gems sitting on the grid.

For me, that is why features matter. They give the game its identity. Without them, many modern slots would feel almost identical after twenty spins.

Which features genuinely change a slot rather than decorate it?

I look for features that change what I am watching or waiting for.

A wild symbol appearing once is useful, but it does not change much. An expanding grid, a multiplier that stays active, or a collector moving around the board creates a different kind of round.

Pirots 4 does this well. Its birds collect matching gems, open more space, and trigger other events around the 6×6 board. You actually follow what each bird is doing.

Money Train 4 goes in the opposite direction. It throws more than twenty possible features into its respin round, including characters that upgrade, unlock rows, or reset spins.

I would call both feature-heavy, but they feel completely different. That is important. A proper feature should change the game, not just make the screen flash harder.

Why are tumbles and multipliers in so many modern slots?

Because they make one paid spin feel longer than one paid spin.

With a tumble, winning symbols disappear and new ones fall into the empty spaces. That creates another chance to connect symbols without placing another bet.

Multipliers add another layer because players can see the potential building. A small win may suddenly matter if a large multiplier lands beside it.

I understand why studios keep using this setup. It is easy to follow, looks good on mobile, and gives players something to watch after the reels stop.

My complaint is that too many games now copy the same formula. Tumbles, sweets, multipliers, free spins, done.

A feature can be popular without every new slot needing its own slightly different version. Sometimes the mechanic fits. Sometimes it feels borrowed.

Do more bonus features always make a slot better?

No, and Money Train 4 is a good example of both sides.

It has more than twenty features, which is impressive. When several characters work together, the bonus round can become genuinely interesting.

But I would never recommend a slot only because it has a long feature list. More moving parts can also make a game harder to read.

Sometimes I open the paytable and feel like I am reading instructions for a small machine. There are upgrades, levels, collectors, resets, locked rows, special wilds, and three bonus-buy options.

For me, the best feature-heavy slots still show players what is happening. You should understand why a win grew or why the round ended.

If the player needs a diagram after every spin, the studio probably added too much.

What is your view on bonus-buy features?

I think bonus buys are useful for testing games, but dangerous for normal play.

They let players skip the base game and pay directly for a bonus round. That sounds convenient, especially when a slot has been cold for a while.

The problem is the price. A bonus may cost 80, 100, or several hundred times the normal stake, with no promise of getting that amount back.

I see players treating the buy price like the feature’s value. It is not. It is simply the cost of entering one high-risk round.

Some markets restrict bonus buys for good reason. They compress a lot of risk into a few seconds and make losses feel faster.

Personally, I prefer earning the feature naturally. It takes longer, but it keeps the session from turning into repeated expensive coin flips.

Why do collecting features and persistent meters work so well?

They give players something to follow besides the balance.

A meter filling up creates a small story. You may need another coin, symbol, bird, or upgrade before something new happens.

That progress feels good, even when the win itself is small. The game looks like it is moving somewhere.

However, players need to be careful with features that appear “nearly ready.” A full-looking meter does not always mean the bonus is close in any useful way.

I think studios know how powerful that feeling is. One missing piece can keep people spinning longer than they planned.

When we review these games, I try to separate real progress from visual theatre. Does the meter carry over? Can it reset? Does it actually improve the next feature?

Those details matter more than the animation.

How should players compare two feature-heavy slots?

I would start with the boring details before watching the big-win video.

Check the RTP version first, because casinos sometimes offer different versions of the same slot. Then check volatility, maximum win, bonus frequency information, and the full paytable.

After that, look at how the feature works. Does it depend on one rare multiplier? Does the bonus need several upgrades before it becomes useful? Can the round finish without doing much?

I also test the base game properly. Some slots put nearly all their value inside the bonus, leaving long quiet gaps between features.

For me, that can get tiring fast. A huge maximum win does not fix a dull session.

The better slot is usually the one you enjoy before the bonus arrives, not only during the best possible feature round.

What do slot developers still get wrong about bonus features?

I think some developers confuse excitement with constant noise.

Not every spin needs an explosion, fake tease, shaking screen, and loud sound because two scatters appeared. After ten minutes, that becomes tiring rather than exciting.

I also dislike features that look important but barely change the round. A new name and bigger animation do not automatically create better gameplay.

The strongest slots usually have one clear idea. Gates of Olympus builds around tumbles and multipliers. Pirots builds around collecting. Money Train builds around feature combinations.

Players can explain those games after trying them. That is a good sign.

For me, a bonus feature has done its job when it makes the slot memorable and easy to understand. It should add tension and choice, not hide weak gameplay under flashing lights.