I was thinking about the older games I use to play, except card games. All the other games needed more than one player.We've invested quite heavily into X-Wing miniatures and played around in the tournament scene. My son and I play quite regularly and enjoy the "building" your squadron and slapping em on the table.
I hadn't discovered the hobby in the SPI and Avalon Hill days but I'm fully onboard with GMT, Lock'N'load stuff etc.
Actually not. There's many cooperative games that can be solo'd and even solitaire games themselves.
Co ops are good to play solo and on the odd occasion you can get together with friends.
Also two player specific games are great with spouses.
This is an advantage of computer games. You can play these games alone.