Corvette Command is a solo narrative campaign game in which you guide convoys in World War II.
Bomber Boys is a free print and play game in which you manage the crew of an Allied bomber in WWII. It’s a dice-rolling and allocation, hand management game.
Donning the Purple is a 1 – 3 player print and play game about political intrigue in ancient Rome. I have the physical kickstarter game and enjoy it as a solo endeavor.
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.