Tiny Epic Galaxies is a great gateway game by Gamelyn Games. It comes in a small box and doesn't take up much room on the table making it an ideal game to take with you on trips or on the go. The solo game is very challenging.
Playing solo is a great way to learn to play a game so you can teach your friends or family to play and look like a pro. Also it is just comforting to just play by yourself and learn some strategies.