We've discussed solo play here before. I guess I'll have to try it to get it. I am definitely into 1 DM and 1 player. Viv and I did that for an Ari and Caper adventure. Ari, the PC, had a smart wild cat, Tude, for a pet. Her sidekick, Caper, was an NPC so I ran the game and 1 NPC in the party and Viv ran Ari and Tude. That really worked well.