The International Obfuscated C Code Contest

The following hints were used for myself but also I offer them for those who wish to more easily follow the code, though that might or might not help that much. If a variable or other kind of symbol is missing or is not what it says here that was by (in some cases) simply missing it or (in other cases) due to having changed things a fair amount; this submission took a lot of work and time to get everything in. One variable, p, is for the encrypted version only.

The following variables are of primary concern (some temporary ones are not documented I think):

• O: how much you spend on oxen
• R: amount spent on food
• E: amount spent on ammo
• G: amount spent on clothing
• O: how much you spend on oxen
• N: amount spent on miscellaneous supplies
• T: how much money you have
• e: ate an ox
• b: hp (hit points, starts out at 666, allows for survival in conditions you can’t in the original) or stamina (kind of a combination - if you get injured and you see the doctor and can afford it you will not keep losing hp but you won’t gain any either).
• A: turn number for setting date (the first week, Monday 29 March 1847 is at 16 so to print the second week day date month and year (though it does it March 29 like the American way) you would do V(A+16)) (note that the date is not set in a variable but rather for printing the date)
• I: unused except to spell out OREGON TRAIL.
• L: amount spent on items at fort (used as a temporary money value for calculations at fort)
• q: event number
• f: flag for injury
• M: total distance travelled
• a: flag for illness
• z: flag for fort option
• K: the FILE * (data file)
• y: contents of data file
• p: used to print (one character at a time) the strings (encrypted version only)
• r: (unsigned) answer to certain questions
• d: son froze to death (and you ate him)
• J: file length read (fun fact: as part of obfuscation in multiple levels, J != strlen(y)!). It’s reused in the V function after being set to 0.
• l: non-zero when hunting.
• W: flag for clearing Blue Mountains.
• Q: got dysentery and went to doctor (I think only if you could afford the doctor but not sure)
• B: if non-zero, can’t afford the doctor, don’t try again (this prevents a flood of the message each turn).
• h: I believe this is if you were injured and could afford the doctor.
• c: hit blizzard.
• X: passed South Pass.
• i: been poisoned; you will be dead shortly (sorry - that’s what happens when you have a pact with the devil!).
• g: how many limbs you’ve had to cut off (surgeon’s cut edition)
• t: temporary array for purchasing at forts.
• u: temporary unsigned int to iterate through array t (and maybe other uses, not sure now).
• v: non-zero means ran out of oxen so as to not flood user every turn with certain messages. But if you buy more that could in theory happen again. Note that some messages might be printed instead of the you have run out of oxen message, if they’re the ones causing it, though I’m not going to say this is in every case as there are a lot of ways for this to happen.
• any other variable I haven’t the foggiest, even if it’s not related to fog (of which there is an event where you encounter fog) - sorry. An example here is m.

When an amount spent (if it happens, not necessarily going to for every variable) spent ends up being < 0 (it’s not allowed to go that low when purchasing) it means that there is an insufficient amount (thus a variable reuse).

The array:

    long *o[]={ &O, &R, &E, &G, &N  } /* animals, food, ammo, clothing, misc. supplies

is used in at least one loop to not have to do checks individually. The variables, btw, are not how many as such (well in some cases it is, although with the number of animals it’s a ‘taken at liberty’ and based on my interpretation of the original 1978 BASIC game) but rather how much was spent on them. As for the ammo: $1 spent on ammo means a belt of 50. That means another variable has to exist (that would be the I one) and every time a purchase is made (at fort or initially) I is set to E * 50.

The functions:

• main(): you know what this is: or…do you?
• k(): the function that determines if you shoot successfully.
• x: uses rand() to get a pRNG number in a range.
• V: the nasty function that decrypts (one character at a time) strings in the data file. Or doesn’t really decrypt it per se.
• Z: calculates address of a block in the file (used by function V and macro S).

The macro:

• S: scanf macro.
• w: death macro which will ‘goto hell’.

If you expect me to try and describe the labels I will direct you straight to line 22!