Developing a brand new online slot

What is this online slot designing blog about?

On the 8th of January we posted up a new page ‘Online slots we’d love to see’ which can be found here. We posted the page on social media as a bit of fishing.

slot machine design

Endorphina responded the next day to say they had watched “The Fisher King”, enjoyed the movie and the theme and are seriously considering the idea of developing a slot based on the movie. Now obviously a lot hangs on whether or not the rights to the movie are available as well as the image rights to the actors (most notably and possibly most tricky being the image rights to the late great Robin Williams).

With that in mind I decided that it might make an interesting blog to tell you about the process of designing an online slot.

I will start off by trying to help design the end product, how the slot will play and what features it will have. After that I’ll be in touch with Endorphina and see where we go from there and try and get as much information as possible about the mechanics behind online slot design.

The slot basics:

For this slot I’m going to plump for a 50 Line slot with a 4×5 reel layout (the same layout as their excellent and quirky Blast!Boom!Bang!).

For the minor reel symbols we are going with the ubiquitous 9, 10, J, Q, K and A. For the major reel symbols we’ll go with 5 main characters:

Parry (Robin Williams)
Jack (Jeff Bridges)
Anne (Mercedes Ruehl)
Lydia (Amanda Plummer)
Homeless Cabaret Singer (Michael Jeter)

The wild symbol will be the “The Fisher King” logo, the free spins scatter symbol will be the Red Knight and the bonus game scatter symbol will be the “Holy Grail”.

There will be no stacked symbols so and slot will be high variance.

Bonus Rounds:

The Red Knight Free Spins:

  • The Red Knight Free Spins is triggered by landing 3 Red Knight symbols. These scatter symbols only appear on reels 2, 3 and 4.
  • 7 free spins are awarded.
  • During free spins the Red Knight becomes a sticky wild.
  • A Red Knight on reel 3 becomes a standard sticky wild.
  • A Red Knight on reel 2 shoots fire to the left, making a sticky wild on reels 1 and 2.
  • A Red Knight on reel 4 shoots fire to the right, making a sticky wild on reels 4 and 5.
  • The logo symbol remains wild but is not sticky.

The Holy Grail bonus game:

We love the old school round the board type of bonus game and find it quite strange that slot companies don’t make more use of it. Parry’s quest for the Holy Grail is a key element in the movie and is perfect for a round the board bonus game:

  • The Holy Grail bonus game is awarded by landing the three Holy Grail scatter symbols on reels 1, 3 and 5.
  • The bonus game is played out on a rectangular board game with 20 squares
  • 4 corner squares, 5 horizontal and 3 vertical squares
  • The bottom right hand corner square is the starting square which becomes a Holy Grail symbol once the game has started.
  • The top left hand corner square features the Holy Grail also.
  • The other two corner squares feature the Red Knight.
  • In the centre of the board there is a large single dice for moving your game piece (Jack & Parry). There are 7 empty boxes to be filled with Holy Grail symbols and there are 4 empty boxes to be filled with Red Knight symbols.
  • There are cash prizes in all the other squares (values of stake level). With the highest next to the Hoyl Grail symbols and the lowest next to the Red Knight symbols. As follows: Start/HG – 5 – 4 – 3 – 2 – 1 – RK – 1 – 3 – 5 – HG – 5 – 4 – 3 – 2 – 1 – RK – 1 – 3 – 5.
  • Once 4 Red Knight symbols are filled (landed on) the game is over.
  • If all 7 Holy Grail symbols are filled (landed on) without having landed on 4 Red Knights, then the game is over, The Holy Grail is found and the jackpot is awarded (this could be utilised as a progressive jackpot or simply a x500 or x1000 jackpot prize).
  • Landing on a Holy Grail also gives a cash prize of 10x stake.

I think that pretty much covers the general idea around the slot. Time to upload this blog live and have a chat with Endorphina before I write any more.

Contingency Plan

Obviously being a movie licensed slot is the ideal situation but should that not be possible then this slot design could easily be turned into “The quest for the Holy Grail”, with the movies characters replaced by quirky intrepid explorer characters, the Red Knight replaced by a fire breathing dragon and the logo wild could be replaced by any number of things, a pyramid symbol for example.

Where there’s a will, there’s a way!


A really good read for anyone seriously interested in designing slots or in a little bit more about how they work:

Elements of slot machine design document