I’ve been doing it for years. I bet a lot of gamers have.
Computers make it a lot easier. You have a computerized opponent with some type of in game AI (artificial intelligence, or in this case just programming.)
Computer games can be played with friends but it’s often not required.
Board gaming and card games I think take a different mind to play alone. I played the board game Splendor today by myself four times after putting it in sleeves. Probably good for the cards but they don’t fit in the box as well. Maybe thinner sleeves?
I find playing games with myself helps me understand the strategy and it’s easy for me to be more than one player.
It can be especially useful when you are deckbuilding and want to see how something plays in a game like Magic: The Gathering. One of my highlights yesterday was playing my goblins deck I have been fiddling with against my new standard landfall deck. Hard to tell with three games. I wish there was more cheap burn spells in red with standard right now in MTG. Seems like black has more good spells to neutralize characters.
So looking forward to playing Friday Night Magic again tomorrow and I think I will always enjoy the puzzle that is a good game. Even when just playing with yourself.