video game character, Undertale, playful pose, pixel art style, colorful striped shirt, blue shorts, heart-shaped soul, action scene, underground setting, fantasy environment, monsters, friendly expressions, dynamic lighting, side-view camera angle, retro aesthetic, detailed textures, interactive gameplay elements, 8-bit music notes, determination, adventure, puzzle-solving, Flowey, Toriel, Sans, Papyrus, Asgore, Frisk, Chara, determination, save points, bullet hell combat, pacifist route, genocide route, neutral route, pixelated flowers, determination, ambient light, 2D platform, sprite animation.