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And even more in these threads:
- Explaining your system through Two Cows TRO edition
- (Surely We've Done This One) Two Cows Philosophy of Gaming
WFRP: You have two cows. One is dead. The other has too many legs.
WFRP : You fed your cows warpstone, because you didn't have the Farming skill. Now you have two beastmen. You are hunted down on sight. Roll to see if you catch dysentery.
Sounds a lot like @Hal's ill-fated Thousand Thrones campaign, although with less Slaaneshi "triple nipple" action.
D&D 3rd ed.: You have two cows. Attempting to milk them provokes an attack of opportunity. (Unless you take the Improved Milking feat.)
GURPS: You have two cows. Now you're out of points and cannot learn to farm unless you choose to be bedridden, in which case you can also have laser eyes.
Traveller: You have two cows. They displace two tons each. Their resale modifiers are +4 In, +2 Na, -2 Ni, -4 Ag.
Traveller: You have two cows. One dies exploring new worlds. The other dies of combat-related injuries in his third term. You retire. Begin play.
TRAVELLER - You had two cows. One died during character generation. The other is controlled by a room-sized computer and eats 75% of its body weight in hay in order to give milk once a week. It's traditional to dim the lights before milking it.
Paranoia: Those two cows are your friends. You would never betray the two cows, would you? Be a happy citizen, praise the two cows. The two cows are always watching you. You don't know how many of your friends are secretly cow-haters. You must seek out those who would harm the cows.
Paranoia: you have two cloned cows, provided to you by your friend, the Computer! You do not trust them. They make strange ticking noises.
Paranoia: Knowledge of cows is treason.
Rolemaster: You have two cows, each with 10 attributes. Each of those attributes has a percentile rating and a second rating that shows its maximum potential. (See chart 5.1)
Rolemaster: You have two cows. You attempt to milk them but fail your roll on the Milking Table. Take an 'E' Lactation Critical.
OWoD: You have two cows. The first cow rules for 5,000 years and is a complete prick. The second cow wears a leather jacket(!) and bemoans his fate.
NWoD: You have two cows. The larger cow is more accurate. (I kid!! I kid!! Try the veal!)