solo rpg solo play solo game master guide combat story conflict strategy emulator theme hex-crawl demo oracle solo gm list video rules pdf cheat sheet roleplay writing mythic dungeon crawl toolbox summary cthulhu beginner gwydion solo-play song list paid plot twist d&d drivethrurpg wisdom tiles theater of mind published solo gameplay listen module solodark tweaks cinematography obstacle ian irvine free module freeform association text-based 2d6 dungeon improvisation inspiration mechanics solve exercise motivation problem review gameplay imagination cheat adventure shadow dark podcast scene choose your own adventure role play killing your darlings