The Seeker In The Forest of Wyr is a solo print and play with just 17 cards.
Dungeons of Darkness is a free solo print and play game about delving into a dungeon and returning with the treasure.
Drive like Hell is a free 18 card print and play game about outrunning the Devil. It was a finalist in a 2020 18 card game design challenge.
Renfield is a free print and play game from Cheapass Games. It’s a trick taking game where the goal is to eat the fewest bugs, as long as you eat one. Renfield, for the unenlightened, is the name of the bug eating madman in Bram Stoker’s Dracula
In Air, Land and Sea from Arcane Wonders, two players battle for control of theatres of operation. It’s a micro game that plays in about 20 minutes and has gotten a lot of good reviews. You can get the free print and play version of Air, Land and Sea at the link.