For many of the games, I ended up assigning one player to be “me” and different personalities to “the other players,” who each had different styles. I also tried my best to stop “myself” from cheating by forgetting what cards “everyone else” had. After all, games are not fun when someone is cheating.
Thankfully, my days of playing board games by myself is long over. However, I still have a tendency to take a long time to calculate my next move since I’m always trying to factor in what everyone else is doing.
I spent 4-5 years playing Avalon Hill wargames alone (Panzer Blitz, Squad Leader, 1776, etc.), trying to play each side's strategy as accurately as I could. I don't know if it made me a better tactician but it certainly threw open the gates of historical curiosity to the point that 12-year-old me knew more about WWII than my parents.
But I design board games now, and boy do I ever play my own games against myself now. I'll play up to 4 players solo for playtesting purposes, no problem. So far the only types of games that it's seemed pretty impossible to do this with are social deduction and party games.
-Lord of the Rings: They have the rights to the books, not the movies, which allows for a ton of creative writing and characters. Definitely the heaviest and most complex of the three, but allows for the most granularity in deck building. Has an enormous card pool.
-Arkham Horror: VERY story driven, cosmic horror theme that draws heavily from Lovecraft writing, but isn't afraid to blaze its own path. Feels very much like an RPG.
-Marvel Champions: Lighter weight than the other two, but an absolute blast to play. Very pick up and play with minimal story, feels like an action brawler. The newest of the three. Deck building is much less of a chore than with the others. You pick a super hero, they come with fifteen hero-specific cards, then pick an aspect (think color from Magic) and fill out the deck with only cards from that aspect.
Aside from card solitaire reviews, Hesse's "glass-bead games" (aka Hipbone games ) and various articles on Game of Life, only  with  seems close enough to what I have in mind (+ variations on Jung's active imagination with tarot, surrealist games), mainly using board games as a tool for thought and modeling beyond the purview of classical game theory.
I would appreciate pointers in that direction.
As a bonus, if you are interested in abstract board games and eurogames, GIPF project  is worth checking out.
Tabletop Simulator absolutely kills my 15" 2015 MBP (integrated graphics only). The interface is laggy, and the fans are running at max after about 10 mins of gameplay.
Not that it doesn't work when there's no dedicated digital alternative that it exists, but its generally my absolute last choice.
I like deduction games like "Mastermind".
I play patchwork and Azul regularly and like them.
"Small World" is a super fun, ultra confrontational game in two player mode.
- Century: Spice Road
- Race for the Galaxy
is a good two player game. It has a simple base game, and then is kept fresh by randomly changing the gameplay with additional rules each play. You can also buy more rule cards.
Sagrada works two player and has a hidden objective element, though I feel it's a little better four player.
10 Days In Africa is a good quick game with hidden information that's playable two-player, but it's out of print so can be hard to find.
* Dominion (Card game)
* Splendor (also mentioned by another user).
* Ikusa (~8+ hour game, 2 to 5 players. A faster-moving version of Axis and Allies)
--* Gomoku (https://en.wikipedia.org/wiki/Gomoku) Played on a Go board
--* Connect6 (https://en.wikipedia.org/wiki/Connect6), also played on a Go board
One of my favorite games is "Acquire", but it only really works with 3+ players. There is a 2-player variant, but its not quite as good.
You can play it with 2 players, it is more fun with 4 though (should either be 2 or 4). Go and chess are classics I enjoy with 2 players, although I generally prefer larger groups. Not very creative, I know.
Keyforge: card game with random but fixed decks.
Splendor, Azul, Century are also good to play with 2 players.
We also enjoy Castles of Burgundy at two players.
Santorini might suit you.
I think Pandemic works well as 2 player, though not all agree.
7 Wonders Duel for combative PvP.
Still, this is a great era for not being bored. There's far more content coming out every day than anyone can consume. That was not the case two decades ago.
A lot of those games are often very story or action driven, and aren't really about successfully navigating a system of interlocking mechanisms like a lot of board games are. There are exceptions out there (XCOM: Enemy Unknown comes to mind, although that was designed by Ananda Gupta, the same guy who designed one of the best thematic strategy board game ever - Twilight Struggle - and he prototyped XCOM as a board game first), but not many.
Logistics video games also seem to work well, like Factorio or any of the Zachtronics games, about making the most efficient system you can to accomplish a goal.