Good Little Tricks is a free print and play card game similar to Hearts, where you try to avoid taking cards. It adds a few twists of its own.
Renfield Card Game
Cheapass Games offers Renfield, a card game about parts, tools, gravestones and “yummy delicious bugs.”
Fantasy Microcosm Card Game
Fantasy Microcosm is a fantasy themed card game for two to four players that uses tit-for-tat card-combo mechanisms. This DIY game requires making a deck of 60 cards.
Agent Decker Card Game
Agent Decker is a print-and-play card game with a spy / espionage theme. The author writes:
AGENT DECKER is a mission-based deckbuilding game for one player where you’ll acquire gear and skills by facing obstacles. The alarm raises every turn, so you must pick who you take out. Do you go for the cool weapon, or take out the security camera?