indie game concept art, Undertale prequel, pixel art style, underground world, monsters, young human protagonist, retro aesthetic, 8-bit soundtrack, puzzle-solving, exploration, friendly combat system, dialogue choices, moral decisions, vibrant colors, caverns, ancient ruins, magical forests, dynamic lighting, side-scrolling perspective, character development, emotional storytelling, unique abilities, hidden secrets, boss battles, heartwarming moments, atmospheric effects, chiptune music, sprite animation, creative world-building, engaging plot, player impact, nostalgic feel.