Genre: Metroidvania

Expert blueprint for Metroidvanias balancing exploration, progression, and backtracking rewards.

NEVER Do (Expert Anti-Patterns)

NEVER allow "Soft-Locks" where a player is trapped; if they enter via a one-way path ("valve"), they MUST be able to leave using current abilities. Always design fail-safe escape routes.
NEVER create empty dead ends; if a player backtracks to a remote area, they MUST be rewarded with a collectible, lore, or currency. Empty rooms are design failures.
NEVER make backtracking purely repetitive; as the player gains movement (Dash/Teleport), traversal through old areas MUST become faster. Open shortcuts to bypass long, early routes.
NEVER hide the critical path without "crumbs"; use distinct Landmarks, unique lighting, or environmental storytelling to build the player's mental map.
NEVER design abilities that serve only one purpose; strictly implement dual-use traversal and combat functionality (e.g., a "Dash" that crosses gaps and dodges attacks).

NEVER forget to save persistent room state; if a player opens a chest or defeats a boss, that state MUST remain saved when they leave and return.
NEVER load interconnected rooms synchronously via load(); strictly use ResourceLoader.load_threaded_request() for seamless transitions.
NEVER track global progression within localized room scripts; strictly use Autoload Singletons for global ability flags and world state.
NEVER use floating-point types for grid coordinates (minimaps/fog); strictly use Vector2i to prevent precision jitter.
NEVER manipulate the SceneTree directly from a background loading thread; strictly use call_deferred().