Developer: Nomad Games
Buy it here
One of the very best things about Love Letter is its concept — you need to get a love letter to the princess, but everyone in the castle is standing in your way, including the princess herself.
Guards might stop you, handmaidens might refuse to deliver your declaration of love, or you might accidentally tick off the Princess and really screw yourself out of a win.
While there is a decent amount of strategy and bluffing involved, Love Letter is extremely easy to pick up and learn, and mostly appropriate for all ages.
While Love Letter is unquestionably better when played face to face with people you know, it's still a fun (and quick) time on PC via Steam.