I introduced this game in Dundee and we played this game together maybe 20 times. We developed a few house rules and one guy played this every workday for most of a year, going on to develop a few more.
I played this for the first time in nearly 2 years last weekend and played it 3 times. Though we had fun, most of the details of our house rules were forgotten. Moral: take notes.
This is an attempt to start.
Being able to force a trade (as in the original rules) makes it a trivial matter for the Things to infect a human - they would probably be able to do so on their 2nd turn and win the game in a 3-player game, given it's now 2 things v 1 human.
It's entirely possible I'm misinterpreting (or it was mistyped).
To encourage trading, we allow a player to search if their trade was unsuccessful.
3: If more than 3 or 4 players are playing, we would shuffle two decks together.
4: In a game with over 5 or 6 folk, the humans need 2 survivors to win. Without 2, the helicopter can't be operated.
5: In a game with over 4 or 5 folk, 2 red cards can be mixed in with a black card, then 1 removed and hidden, before those are added to 5 per player minus 2 (so there's a 2/3 chance of there being 2 things at the start).
6: We would discard cards face up after searching. This was partially due to practicality - having two discard card piles isn't very convenient. Also, seeing a player discard high reds allows for a 'confirmation' that they're human. Theoretically, if a player picked up a card, then discarded a different - red - card, it would be clear that they were the thing. But whether because the thing never picked up a low card it would later need to discard or because we didn't watch each others cards in that kind of way, it was never an issue.
This was probably a mistake though - in the 3 player game I played,
7: We played without the 'bite'/flamethrower cards. Bloodtesting is where the meat of the game is - either pretending (as the thing) that you've uncovered another player's thing-ness or simply in genuinely trying to work out what's going on as a human.
The bite/flamethrower mechanic seems to encourage folk to be conservative with their bloodtesting, which actually reduces the amount of tension by turning it from a game with tiny scraps of information into a game with nearly none - the latter feeling too random.
Also, it reduces the impetus for trading.