It’s Official – Many Spider Solitaire Programs Are Biased

It’s official. I believe many Spider Solitaire programs are biased – both for mobile phone and PC. Biased means if a player wins too many games, then the software will stack the cards against him in subsequent deals. Apologies if this comes across as a broken record, but “spider-software-bashing” is what inspired me to create this blog in the first place.

Let me state at the outset this is only my belief, and it comes with a number of caveats. I won’t expect regular readers to agree with my POV, but at least they can hopefully see where I am coming from. Following the rot13(erirefr fuvg fnaqjvpu) principle, I will start with a large number of caveats, then bring in the good stuff, and finally summarise these caveats. I assume we are always playing at the four-suit level (although it is possible to perform similar experiments with less than four suits).

The Caveats

  • Firstly, I don’t expect regular players to be able to reproduce my results. You will need a very good aptitude at the game. In particular you must be able to win practically every game at the four-suit level with enough perseverance and skill. Fortunately undo/restart is permissable (but not reject). Once you reach that ability you also need a “burn-in period” i.e., play enough hands to let the software deduce you have a good very aptitude for the game.
  • Secondly, I don’t have very many data points. The point of this article is to merely explain why I believe many programs are biased, and I am not claiming conclusive proof. Ideally, if time permits, I would prefer to play 100 games instead of 10. Oh, did I mention I am returning to work on Monday? In any case, if you are intelligent enough to play decently at the four-suit level then you are intelligent enough to draw your own conclusions.
  • I have no convincing explanation of what a software developer would gain by rigging the RNG.
  • A conclusive proof will entail some detailed knowledge of statistics (e.g. what is the meaning of statistically-significant, Komolgorov-Smirnov test, etc). I am nowhere near being in a position to submit a paper to Journal of the American Statistical Association.
  • I tested this on an earlier version of Ninja Monkey’s code, not the one I’m currently using now for the current game.
  • If you are stuck at 10-20% win rate then the bias is either non-existent, or doesn’t concern you. If you are winning above 20% then this is probably relevant. If you are serious about improving your game then all bets are off: your win rate is irrelevant and this is most definitely worth paying attention to.
  • I write this with a heavy heart – one of my readers plays a certain online server, which I now suspect to be biased.

Now Onto My Actual Claims

The certain online server in question is this one. Initially I thought this was kosher after some “experimentation”. However, one of my recent losses cut a little too close to the bone. I then made a serious effort to win 10 consecutive games for the first time – using RESTART if necessary. Note that the software forbids undoing 2 or more moves in a row (and single undo is illegal after dealing a row or removing a suit). I immediately sensed something was off.

I did manage to win all 10 games, but most of them were practically unwinnable without undo/restart. And not for lack of trying. Needless to say, if a Spider Solitaire program penalises a player who wins a few too many with undo/restart, then you can guess how it will treat a player who wins a few too many without these privileges.

Bad Beat

Listen To The Beat

As you might have guessed, I recorded the identity of every card in each of the 10 hands and ran Ninja Monkey’s algorithm. NM played each hand 50 times, for a total of 500 hands. Only for 2 hands did NM manage to win at least once. Whereas for random hands, NM should practically always win at least one in 50. I had similar results for a number of different programs.

Admittedly I may have tilted after a few games and failed to play to the best of my ability. But if anyone accuses NM of doing the same to corroborate my claims I don’t wanna hear about it.

I should point out one or two hands were grannies. Not exactly walkovers, but I would expect even my grandma will have a legit chance of winning sans undo. The term GRANNIE was apparently coined by a Scrabble expert – if you get all the power tiles then even your grandma can’t rot13(shpx) it up. In any case, one of my victories can safely be described as an EARNING.

My gut feeling says the software company wants to “equalise the players” so that (ideally) every single hand is either won by every player or lost by every player. Hopefully I don’t need to explain why this is a very bad idea.

Since it is beyond the scope to discuss the detailed mathematic specificity (with apologies to Kevin Rudd), I will simply present the initial game state for each of the 10 hands. I recommend the reader play the hands out for himself – first attempt to win without undo/restart, and if that fails then see how easy/difficult it is to win with undo/restart. The reader can also perform a control experiment by dealing 10 random hands. For extra credit: try to guess which two hands gave Ninja Monkey at least one victory in 50 tries.

List Can Be Any Colour As Long As It’s Black

As a result of this experiment, I have personally black-listed a number of Spider Solitaire programs, both for PC and mobile. From now on I only accept recognised programs like Microsoft Windows, or programs with source code (e.g. a GitHub project).

Games that “look and feel slick” are a red flag. Most of the bad programs I have encountered go beyond the basic “six-week-internship-prove-you-know-Javascript” thingy. While it is true that correlation is not causation, I would rather put my money on something that looks tacky instead of slick. Yes, the tableau cards do not flip automatically which is admittedly stupid, but at least you know what you’re getting. And the developer seems like a cool guy – anyone who’s willing to publish their name like that is almost certainly kosher. I found two look-and-feel-slick mobile phone apps, both dodgy and both had a similar “auto-complete” function when every column was either empty or reduced to a single straight-flush of any length. They’re probably from the same company.

Conversely if something looks like a basic implementation of Spider from someone who is learning the ropes of version-control in GitHub, then it is reasonable to assume there is no effort to punish a player who wins too often.

Yes, I hear you say, what possible motive do software developers have for punishing players who perform too well? True, not all Spider apps offer players a chance to enter competitions for “free” provided they sign up for PayPal, give away credit card details, their home and work addresses and the number of times they use the toilet every day. I was asking the exact same question and don’t have an answer. What I do know is that my numbers don’t lie – if Ninja Monkey says something is off, then Ninja Monkey says something is off.

IMHO, the onus should therefore be on software developers to prove they are kosher. Guilty until proven innocent if you pardon the inversion of a terrible cliché. If you can write a decent half-page essay on poker player Veronica Brill without help from Google, then you will certainly know where I am coming from.


I have decided many Spider Solitaire programs are not worth playing for both mobile phone and PC and I have blacklisted a number of those. But I wish to reiterate the fact this is my opinion only and my claims may well be difficult to substantiate for average players. Do not expect to see my name in lights if you subscribe to Journal of the American Statistical Association. But at least the reader has something to go on if he wishes to investigate for himself.

Finally, I wish to apologise if this comes across as a long-winded rant. But I believe this topic was worthy of more than the usual number of paragraphs.

And if you believe that some program is biased then you can also sit back and listen to the beat.

I guess that got pretty pathetic

Some time ago I played with a Spider Solitaire app for iPhone. And I have to say its features are more bewildering than the infamous “At first condemn our very feeble excuse for everything that follows constant negative press (7)” tweet from 2017 US politics.

Earlier this year I could load the program and deal a hand. Unfortunately I couldn’t see any cards!  I eventually decided to update all my apps, but only because Gmail also needed an upgrade for some reason. A few days ago I played my first game and lost narrowly. On the very next game this happened:

(Text version):

Suits removed: Diamonds, Spades

Stock: 0 cards remaining

Column 1: Ks

Column 2:

Column 3: Kh,Qh,Jh,Th,9h,8h,7d,6d,5d,,4c,3c,2c,Ad,8d,7c,6c,5c,4c,3c,2c,Ac

Column 4:

Column 5: 6h,5h,4h,3d,2d,As,2s,Ah,7c,6s

Column 6: ?,8c,Qd,Jd,Tc,9d,8s,7s,6c,5s,4s,3s,2h,Ah,9c,Kh,Qh,Js,Td,9s

Column 7: Kc,Qc,Jc,4d,7h

Column 8:

Column 9: ?,Kd,Qc,Jc,Tc,9c,8c,5h,4h,3h,2h,Ac

Column 10: Kc,Qs,Jh,Ts,9h,8h,7h,6h,5c

Ummm … excuse me? Do I not even get a chance to turn over the last card in Column 9? Like I said, this is more bewildering than the infamous “At first condemn our very feeble excuse for everything that follows constant negative press (7)” tweet from 2017 US politics. Don’t say you weren’t warned.

At the risk of insulting the intelligence of Captain Obvious, I have removed two suits and obtained three empty columns. I know from experience this does not automatically guarantee victory (especially if you are playing a certain server). But this game state is not even close to being one of the exceptions. I leave it as an exercise for the reader to verify the game is mathematically won regardless of the permutation of unseen cards.

Not every Spider Solitaire player has above average IQ and all game developers must cater to the whole market instead of a single expert player – yes, I get that. But whoever wrote this software doesn’t understand the fundamentals of the game. Therefore I am deleting this app.

The good news is Humanity has not (yet) been completely surpassed by its Artificial Intelligence counterpart. While I cannot pretend to understand the detailed game-theoretic specificity of AlphaGo’s Move 37 against Lee Sedol I can still sleep at night knowing AI has some catching up to do when it comes to playing Spider Solitaire.

Out of curiosity I clicked the magic button to see what would happen. The app yanked a full set of clubs from various columns and moved that to the foundations. I’m not sure how this esoteric piece of knowledge will help me in future, but I guess knowing this fact can’t hurt either.

Just In Case You’re Really Bored: can you win the above game with only two empty columns instead of three?

Just In Case You’re Really Really Bored: can you win the above game with only ONE empty column instead of three?

Just In Case You’re Really Really Really Bored: Write a 5000 word essay explaining why move 37 at P10 is more awesome than my attempt to “improve” Grant Woolard’s Classical Music Mashup IV.

Okay so what is this Solitaire Cube thingy all about?

Solitaire Cube

It would be nice if the Solitaire Cube combined my talents of playing Spider Solitaire well and solving Rubik’s Cube (and if there is no cool music I can always play piano at the same time) but apparently they have tournaments where you can play for money. We’re not talking small amounts of virtual money plus a small percentage of dot com stock options indexed to inflation but real money.

Solitaire Cube is your regular i-Phone app with the usual eye candy, cool music and/or sound effects – and best of all it takes the tedium out of shuffling the cards. It was developed by Tether Studios and powered by Skillz, an eSports platform that manages the $$$$

Players are matched with opponents with similar skills in real-time and world-wide. You are scored according to certain rules (which will not be discussed in detail), so even if you can’t win you are still rewarded for partial achievements, such as exposing most of the cards. If you score more than your opponent, then you win the $$$$.

There is also a 5-minute timer, so the game ends as soon as you run out of time. Or you can quit early, cut your losses and take the bonus for time remaining. There is a practice mode where you have virtual currency (Z coins, minus the dot com stock options as described above). Once you are comfortable with practice mode then you can go to the Pro League.

There is something similar for Spider Solitaire Cube, but I described Solitaire Cube first because that seems way more popular (Klondike is much better known than Spider). Besides I would expect former and latter to have much in common.

So that’s the theory, but don’t give up your day job just yet

If I got word of mouth from a trusted work colleague then I might seriously consider wanting in on this. But I heard about Solitaire Cube only because I play way too much match-three games on my mobile and can’t be bothered getting rid of the ads.

There seems to be a growing scourge of low-quality games that are designed to cheat. For instance, a game might be advertised as free-to-play but in reality it is pay-to-win. Or the gameplay itself is lame. Or there is false advertising (think Evony). And don’t get me started on Hero Wars. Solitaire Cube seems to be no different: a simple search (hint: name the largest subsidiary of Alphabet Inc.) reveals a lot of negative reviews. Without going into detail here is a list of complaints:

  • Player’s score is less than it should be
  • Practice hands are much easier than Real money hands (sound familiar?)
  • Frequently crashes
  • Lousy customer service
  • Don’t know if opponents are humans or bots (or if they are same skill level as you)
  • Can’t review opponent’s video ergo don’t know if he legit won. Don’t even know if they play the same hands.
  • The vigorish is worse than Las Vegas
  • You have to deposit $10 into Paypal account, then they ask you for your location to see if you’re eligible for tournaments (wrong location -> no entry).
  • Fake positive reviews.


I’m not sure how many of these complaints are legit. For example, players are more apt to remember the time when the game crashed when they were doing well, but not remember the 10 times the game crashed and they were doing badly. But there are some undisputable facts. If you are betting 25 cents to win 42 cents then the vigorish is 16%, which is worse than Las Vegas. Nobody can argue with the math. And there are things that don’t pass the sniff test, because IMNSHO game developers should not only be doing the right thing but be seen to be doing the right thing. I won’t go into exhaustive detail; I will let the reader draw his own conclusions.

Let’s test this software … or let’s not.

If you read this blog regularly, you will know how to test the Random Number Generator. But I believe it is not worth my time to do the same experiment, mainly because I need to set up a PayPal account. There are other issues, but the PayPal issue alone is enough to turn me off. I leave this as the proverbial exercise for the reader 😊