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