The International Obfuscated C Code Contest

A 27^th IOCCC Winner

Don’t tread on me award

Cody Boone Ferguson ioccc@xexyl.net
https://ioccc.xexyl.net
Twitter: @xexyl

The code for this entry can be found in prog.c

Judges' comments:

To use:

make
WAIT=100 WALLS=0 CANNIBAL=0 ./prog
# Start pressing some arrow keys

Try:

make test

WAIT=75 WALLS=1 CANNIBAL=1 ./prog

./prog

SIZE=-1 ./prog

CANNIBAL=1 WALLS=1 WAIT=50 EVADE=200 ./prog

WAIT=75 GROW=-1 SIZE=5 CANNIBAL=1 ./prog

CANNIBAL=1 WALLS=1 WAIT=0 EVADE=1 MAXSIZE=10 ./prog

Selected Judges Remarks:

As the Gadsden flag warns, beware of the snake! This game has a number of configurable pitfalls including walls and snakes.

There is a good deal of useful documentation that is provided with this entry:

gameplay.markdown (gameplay.html)

Documented game features!

terminals.markdown (terminals.html)

Information about terminal capabilities, dimensions (setting and how to restore sanity if it causes any problems) as well as colours (limitations etc.).

troubleshooting.markdown (troubleshooting.html)

Workaround for various game features

bugs.markdown (bugs.html)

Bugs and things that might seem like bugs but are not.

chocolate-cake.html

Because most of us could use some Double-layered Chocolate Fudge Cake!

spoilers.markdown (spoilers.html)

Read ONLY if you really must give up trying to de-obfuscate!

Author’s comments:

Feature-rich curses implementation of the Snake game (with many gameplay modes and options)

Snake has two cheat modes (passable walls and self [cannibalism]), a drawing (or practising) mode, can play by itself (and win!), is coloured (included snake-colours.sh and play.sh scripts compile in player-selected colours) and there are many other play modes (many more can be devised with the imagination and the environmental variables; see gameplay.markdown / gameplay.html for many examples) and options. You can pause and there’s even a built-in test unit for some features! The following variables change the game in the following ways (all can be combined):

The speed of the snake (how many milliseconds to WAIT for input before moving; default 231 milliseconds and you can move faster by pressing a direction key quicker or even holding it down).
If the bug (to eat) will move (EVADE) after user-specified number of snake moves (default 300, 0 disables).
If the snake can go through WALLS (coming out at the opposite wall) (default 1, yes).
If the snake can go through itself (CANNIBAL) (default 0, no).
The initial SIZE of the snake (default 5).
The size the snake must become in order to win the game (MAXSIZE, default 997).
How much to GROW each time a bug is eaten (default 5, can be negative).
How many moves (SHED, default 0, disabled) before ‘stretching’ (grow) (SHEDS, default 5; can be negative). This is how snakes grow in the wild so is a misnomer here because snakes don’t grow in the manner that the original Snake game was designed.
- Exception: if the bug is eaten the counter isn’t incremented.
A drawing/practising mode (WAIT < 0 makes timeout() set blocking read).
Computer plays the game (WAIT=0) EPILEPSY/STIMULATION OVERLOAD WARNING included in the relevant section (this goes for a low EVADE value too).
Grow-Shrink mode (Positive and Negative Winning) mode (see gameplay.markdown for more details).
The dimensions of the game (this is actually a terminal thing but I document how to do this and its potential pitfalls) (LINES , COLUMNS).

There are no complicated command line invocations; it’s just a matter of passing into the game descriptively named variables and I include a script that sets up many different gameplay modes (gameplay.markdown and play.sh).

The gameplay.markdown (gameplay.html) file has all the information on what the game looks like, how to play, the different types of modes (that I have thought of so far) including all those in the above list. Along with the play.sh and snake-colours.sh scripts it’s probably the most important file for players.

The gameplay file is long but it includes game printouts as well as explaining the many different gameplay modes. The play.sh script automates most (if not all) of the gameplay modes described in the gameplay file (it also allows you to change colours like snake-colours.sh) as well as the judges' suggestions (that I don’t document so as to not spoil them). You can pass in environmental variables to both scripts though obviously some will conflict with different options in play.sh.

Probably just as important is chocolate-cake.html with an old but wonderful recipe (because the judges love chocolate and who can blame them? - also it goes with one of the IAQs I include later).

The troubleshooting.markdown (troubleshooting.html) file has some advice on potential problems (and things that might appear to be problems at first glance but are not) that I have thought of or encountered.

The terminals.markdown (terminals.html) has a variety of information specific to terminals from input/directions, dimensions, sanity and colours: a sort of troubleshooting guide for terminals with some additional information.

The spoilers.markdown has a variety of information including some of the obfuscation techniques and a bit of how it works.

The bugs.markdown (bugs.html) has a list of known bugs and things that look like bugs but aren’t as well as documenting a built-in test unit for some features.

Because all IOCCC entries should have a man page I have included one (even though much of it is what’s also above). To render try:

    man ./snake.1

The COMPILING file has a few portability notes and the HACKING file has some information on how one might modify things, things that could be implemented (and how to/how not to go about some of the things) as well as some other information on the entry (some of which is deliberately not true - a variation of misleading comments). These files are probably insignificant.

I will have more information about this entry at https://ioccc.xexyl.net/2020/snake after the winning entries have been published.

For the files I recommend looking at the html files with a browser; this particularly goes for the gameplay.html, bugs.html, terminals.html and troubleshooting.html - along with the most important one chocolate-cake.html.

‘Bugs’
NAQs/IAQs (Never/Infrequently Asked Questions)
Winning thoughts, dedications and thanks

‘Bugs’

‘The screen keeps showing bugs!’ Well yes, that’s rather the point! Help out by eating them. Keep eating them until you win! Then you will have the satisfaction of getting rid of the non-bug bugs! :)
The Snake in the game doesn’t fly (yes there are flying snakes). For other snake madness see the reports of ‘human snakes’.
Technically walls, snakeskin and the snake itself would not be an obstacle in real life. The shed snakeskin is not an obstacle but walls can be and so can the snake itself. Also snakes grow by moulting (technical term for shedding) so when the snake leaves its snakeskin behind it really ought to grow but instead it shrinks; this means negative shedding ought to have the snake grow and positive shedding have the snake - what? It’s a misnomer: it took fewer bytes and the negative shedding is a positive consequence of unsigned arithmetic.

On a more serious note look at bugs.markdown (bugs.html).

NAQs/IAQs (Never/Infrequently Asked Questions)

Do I have any inspirations for this entry?

There are two in particular. First is a long time mate of mine wrote a bash implementation of Snake several years ago (uncoloured, no cheat modes, hardcoded dimensions etc. - in fact everything was hardcoded).

Back then I had thought of making a curses implementation of it but I never got round to it. When the judges announced that the 2020 IOCCC contest would be open from late December 2019 through 15 March 2020 I started thinking again on what might be a good entry. By chance I thought of the Snake game and so wrote it finishing the implementation of everything on 8 November 2019. Did I say everything? That’s an unintentional lie; I thought it was everything but I implemented many new things after that. In fact I have numerous times thought I was done only to have added yet another feature - or two or three or more!

Second is the old Atari game Surround. There were a few modes as I recall. The object of the game was to surround your opponent so that they would run into you, the wall or themselves. The opponent was either the computer or another player.

In one mode you could go through walls (that’s where I got the idea to do likewise). There was also a drawing mode where you could just move round making different designs though that this is in my entry is a happy coincidence (because timeout() will block when it gets a negative value). It’s true that in my Snake it’s not quite the same but it’s close enough. Perhaps it can be made more like Surround if it grows every movement but then depending on the max size of the snake the game might be over fairly quickly (I don’t remember how it was done in Surround).

In Surround each move you made you would grow in size by one. This is what inspired the shedding mode. Anyway I always loved the game and it’s similar to Snake in several ways.

Are there any features I thought of that I wanted to implement but did not get to for some reason or another?

Yes. I thought it would be fun if there were other obstacles for the snake (in my mind I was thinking of barriers like the walls but in the field).

I also thought it would be fun to have more than one bug at some point after say the snake gets to be some size. One of the reasons I didn’t do this is because I was trying to save iocccsize bytes. I never got round to this though and I feel that the features I have implemented are far more interesting and fun.

Another idea is having portals or teleportation but there are a number of problems with those that would have to be worked out too.

I would have loved for it to be practical to support diagonal movement but as I describe elsewhere it’s not. That’s perhaps what I regret most. It would be possible to choose letters instead of arrow keys but even if that fit in the size restrictions how would I show the head? I looked at the extended ncurses character set and I didn’t see any diagonal arrows. I suppose I could have it not show the arrows but then that brings an old problem back.

Nevertheless I am quite happy with the features in the game and I hope everyone who plays it enjoys it as much as I enjoyed writing/playing it.

Are there ways that one can make this game easier?

I can think of at the least the following:

Bigger screen will allow for freer movement (at least for more time?).
Increasing the movement (key press) wait to give you more time to choose (though this slows gameplay down).
Decrease the size of the snake (and growth size) though over time the size will become more and more problematic. But see the next item.
If you set a high growth size you don’t have to worry as much about running into a wall or the snake itself for as long: because the check if you win is done when the snake size is increased: if you’re 15 away from the max and each bug you eat you grow by 11 then it won’t take as many bugs to win as it would if the grow size was 3. This applies to shedding size too.
If you want to show off keep walls passable and enable cannibalism. It won’t be a challenge then but at least you could show your final score?
Decrease the max size.
And the one that applies to learning new things and getting more things done also applies here: remove all sources of distraction; turn the phone off, lock yourself in a soundproof room (refusing to get up for anyone or anything) and delete all your social media accounts for starters. Okay you don’t really have to do the latter one but it can’t be denied that they can be very distracting! As can phone (calls and otherwise). And visitors calling. And being on this planet.
If you don’t want a challenge at all you could just set the start size to be the max size or very close to it. In fact if you have the shedding size to be even one on every move even if you normally can’t win with the same size screen you might find it happens much more easily! You could of course play with these paramters in different ways together - there are certainly different combinations than I have given.
Of course you could also enable one or both cheat modes. You might be considered a filthy cheat but both modes are quite fun (one being enabled by default; does that mean it’s not actually a cheat mode?).

Are there ways to make it harder?

Decrease the size of the game.
Decrease the size of the snake growth (and initial snake size).
Make the snake go faster (decrease the time the game waits for input).
Hold down the direction keys to move faster; this is something I do often though I have always had extremely fast reflexes and amazing eye hand coordination (at least after glasses and the three eye surgeries?). Admittedly I don’t find this makes it any harder but it does make you have to react faster.
Be reckless (i.e. increase the chance of a wreck, a most amusing contradictory idea if you ignore etymology).
Look away for a moment every so often or have a conversation with your best mate, partner or family member whilst playing.
Make walls impassable and disable cannibalism.
Make the bug move more frequently (this can be a real problem when you can’t go through the walls!).
Get used to going through walls and then try with it disabled.
Set the max size to the maximum (MAXSIZE=-1 should do it).

And if you’re a show-off you can try:

Closing your eyes (maybe better to practise with one eye open first or even in practice that is drawing mode?).
Have someone tickle you.
Watch a comedy show or have a laugh with a mate or partner or family member.
Have your partner tease you.
Speak on the phone with someone (paying attention to both). Come to think of it I have actually done this though not to show off but rather it’s just something I’m capable of…
Watch a film at the same time.
Sneeze and/or cough.
Have breakfast, lunch, afternoon tea, dinner or some other meal.
Get pissed out of your mind to make it difficult to think (please do not drive!).
Do more than one or all of the above at the same time (the longer the snake becomes the more often you should do these things).
Eat a great chocolate cake. Actually you should do that whether you’re trying to show off or not. Sleep, bathe, eat chocolate cake, play Snake, eat chocolate cake, play Snake, sleep, … For a great recipe see below.

But if that’s not enough I don’t know what to tell you other than suggest that you make use of your talents for financial gain or at least a world record. Either way I tip my proverbial snakeskin hat to you (animal cruelty but a pun is a pun and every pun deserves to be shed).

How do snakes grow in real life?

They grow through a process called moulting - shedding their skin (other creatures also moult). This takes place over some days and unlike humans snakes never stop growing (though growth slows down as they mature). I chose the variables SHED and SHEDS for simplicity and because the words are shorter. I don’t like the words because it’s rather a misnomer but what I had chosen before was longer - STRETCH and STRETCHES.

Any other interesting things about snakes?

For the fascinating science behind snake slithering see Snake walk: The physics of slithering. For the bizarre thought of snake human hybrids see human snakes. The latter is hard to comprehend and there are some sad tails (tales) in there too because I believe that people actually believe in this (how/why I do not know) and they really do tell the truth as they see it (even if impossible).

Why can you go the opposite direction and so immediately die when not cannibalising?

When Ilya Kurdyukov was playing with this he questioned why this is possible when other implementations don’t have it this way. There are a few reasons.

First is that the friend’s implementation had it that way and it had been a long time since I had played it (if I ever did? I don’t know now: I played so many games over the years and the game most alike it that I played is Surround, as below).

It also is the way it is in Surround.

It makes cannibalism mode very interesting.

And I happen to like it the way I have it. In the end a snake isn’t an obstacle for itself but in the game it is and I went all the way instead of only halfway.

It also would take more bytes and that’s a problem with IOCCC rule 2b.

But if you have a problem with it you can always enable cannibalism and keep walls passable and not worry about dying.

Do you have any DELICIOUS CHOCOLATE CAKE recipes?

Why yes I do! So good in fact that even my late stepmum who didn’t even like chocolate (except white chocolate) loved this cake. It’s a double-layered chocolate fudge cake. See the file chocolate-cake.html for the recipe. Note that it’s a complicated but it’s well worth it!

I included it in all my entries this year because if any of them won more people can have this recipe; also it might help remind the judges that they really should have their cook bake it so they can all - including the cook should they also like chocolate - enjoy the cake whilst judging (and otherwise - it’s a big cake and very rich). Sadly they didn’t get to enjoy it during their judging due to the pandemic but maybe next time (or they can do on their own).

Do make sure to pay attention to all notes!

A note on the icing and room temperature

Please be advised that the note there that talks about the icing being difficult in too warm room is rather significant; unfortunately with SARS-CoV-2 this might be more of a problem depending on how long it lasts and where you reside. If necessary use the refrigerator or else air conditioner to cool down the place.

What are the files prog.2.c, prog.3.c, prog.3-j.c and prog.alt.c ?

I submitted three Snake versions; these are the other layouts for those few (or more likely none) who are interested to see them.

The prog.2.c has more digraphs but I think no other significant differences.

The prog.3.c is in a more artistic layout (a backwards S), has at least one additional obfuscation technique (see spoilers) but it also has more digraphs and as the judges said they feel that digraphs are dated so that’s probably why they chose the first layout. The prog.3-j.c version is prog.3.c with a shorter J define.

The prog.alt.c version is the one that allows for customising the bug colour and it’s used in both snake-colours.sh and play.sh. It also calls erase() first, clearing the screen, which the play.sh and snake-colours.sh scripts also both do.

Author’s dedication:

Winning thoughts, dedications and thanks

Once again I’m honoured to win along with some of the other veterans who I have a huge amount of respect for; there’s Don Yang, Dave Burton, Yusuke Endoh and Edward Giles all of whom are amazing programmers. I’m especially proud to win besides Dave Burton and Yusuke Endoh but Don Yang and Edward Giles too.

But there are some others who I don’t remember like Ilya Kurdyukov (who’s offered a lot of interesting thoughts on Snake and who plans to have his own version after the entries are published), Nathan Otterness, Nicholas Carlini (whose entry is an absolutely brilliant abuse of printf - and I totally agree with the judges comments that your entry is so novel that it’ll be worth special mention in the future Best of IOCCC list!) and tsoj too.

Well done and congratulations to all of you again! Thank you for submitting the wonderful entries and I’m honoured to have my two entries beside yours!

To Dave Burton I thank you for your wonderful comments as well as pointing out that even with prog.orig.c it probably would be better to make use of the alt target instead of naming prog.c prog.orig.c. You’re quite right, I had thought of it but you brought it up so I could correct it. Much appreciated mate.

I would like to dedicate this entry to my wonderful mum Dianne Ferguson whom I love with all my heart and soul <3 Thank you for being the best mother imaginable! You’ve been there for me in the darkest of my hours without question without complaint and with all the love, compassion, empathy, sympathy and devotion anyone could ever ask for. Bless you again and again and again dear mother.

I also want to dedicate this to Vicky Wilmore who has given me a lot of love the past few years and who was there for me in some very dark times. Thank you Vicky sweetheart from the bottom of my heart and soul. Although we have parted ways, whether for now or for ever, you will always always always have a place in my heart and soul xxx

I would like to thank my dear friend Martijn Schoemaker for encouraging me in my programming over the years and who I owe a great deal to. Thank you for believing in me and my programming abilities (and other abilities) even when I couldn’t believe in myself! Very much appreciated especially coming from an amazing programmer who I have huge admiration for!

I want to thank Ilya Kurdyukov for his helpful comments, suggestions and reporting the problem about half-width/full-width char spacing. He’s been playing with some versions of his own and will have them on GitHub after the 2020 IOCCC winning entries have been published.

Finally I want to thank Leo Broukhis, Simon Cooper and Landon Curt Noll for continuing to hold the contest after all these years - and for having selected my entries. It’s a huge honour; thank you! I also happen to love your comments as well as the award titles. And yes indeed ‘most of us could use Double-layered Chocolate Fudge Cake!’