Dominion:
Underworld Transgression started as a joke. It's now a (mostly) playable expansion with around eleven cards themed around criminals and sharing a loose common mechanic: cards that fight amongst themselves like petty thugs.
Among the cards solidifying this theme are:
- Catacombs, a powerful but perilous drawer/trasher that "trashes" cards into a shared mat where they can be drawn by other Catacombs users;
- Outlaw, a card that gives opponents with at least two cards worth at least $5 each in hand curses (note that Outlaw is such a card!);
- Slum, a cheap village that cannot draw cards in the presence of opposing slums;
- Blackmail, a card that gives out "scandals" that initially handicap a player but provide free trashing.
The cards are available here, conveniently sorted into lists of cards that need lots of feedback and cards that are probably balanced enough for playtesting:
https://docs.google.com/document/pub?id=1la8dGiAIxe6jZqWlGdDuGJlb0Z2icimbWBxrSIOiBUMOld designs for retainer and some other cards are preserved below, so the old discussion still will make sense to newcomers.
As for why the name was changed, interested playtesters decided that "Underworld" had more of an infernal connotation than a criminal one.
SLUM (revised)
--
+2 Actions
Each opponent may reveal a slum from hand. If nobody does, +1 card.
Action - (2)
HIGHWAYMAN (was BRIGAND, changed b/c this name might be more recognizable)
--
+1 Action
+(1)
Each other player reveals his hand, then discards the card with the highest cost from his hand.
Each other player draws a card.
-
Action/Attack - (3)
It's a very, very spammable attack that interacts wonderfully with any card-discarding attack. It is better than silver for minion players - and the hand reveal lets you know if you should use minion's attack! It is also powerful against mid-game opponents, where estates give much less protection against the attack, but it won't help you get to $6.
EDIT: STILL MORE CARDS
MINSTREL
--
+1 card
+1 action
If any minstrel remains in the supply, +$1, trash a card from your hand, and gain a minstrel.
-
ACTION (3)
The dirty hippie plague! I'm sure conspirator players will love it. Minstrels aren't criminals, but they weren't the most respected of personages (see also: courtesans), so they fit.
RACKETEER
--
+$2
Each player reveals the top three cards of his deck, discards either all the treasures
or all non-treasures from these cards, then returns the others to the top of the deck.
ACTION/ATTACK (4)
RETAINER
--
+1 card
+1 action
+ 1 coin if you have no retainers in hand. Each opponent discards a retainer or reveals a hand with no retainers.
-
ACTION/ATTACK (2)
Back in the day, nobles kept "retainers" as private armies of thugs, hence the (somewhat obscure) name. The +1 coin if you have no other copies in hand means it's quite inferior to peddler - may try a version without this nerf. The $2 price point is probably too cheap for the nerfed version and too expensive for the unnerfed version.
UNNERFED RETAINER
+1 card
+1 action
+$1
Each opponent discards a retainer or reveals a hand with no retainers.
-
ACTION/ATTACK (4)
This would definitely be a powerful $4 card - however, peddler alone isn't enough to win, so it would be interesting to see whether a player spends $4 buys monopolizing this stack or doing something else that actually gives them a chance of winning.
This card is prisoner's dilemma incarnate - if several players get it, I am hoping they all end up with sucky hands and no benefit.
Edit: On further recollection, Retainer is just as obnoxious a card in multiplayer as the old "Slum" was (thanks to wanderingwinder for feedback), and since it's an opening buy, it dramatically exacerbates first-player advantage. Not sure if i should keep this card.
Another Edit: peddler can EASILY make the difference between a win or loss, see
http://dominion.isotropic.org/gamelog/201107/05/game-20110705-210348-6027cc16.html