Locked crate

The locked crate is a special type of container. Unlike other containers it is not recommended to destroy this crate. Instead a matching key can be found that can be inserted to open the crate. Afterwards a bunch of useful items will be dropped.

Spawning behavior
The color of locked crates is matched to the area it is found in. If a key exists you can be sure that somewhere in this area a matching crate exists as well and vice versa. There will never be more than one crate per area.

The first area's crate is red and found in Level 1-3. The key is always dropped by the elite enemy found in Level 1-2.

The second area's crate is green and found in Level 2-2 or Level 2-3.

The third area's crate is blue and found in Level 3-2 or Level 3-3.

Types
All locked crates will drop some ammo and if the player is low on health instead also some medicine.

Locked weapon crate
The locked weapon crate will drop a random weapon with drastically increased chances to spawn particularly powerful weapons that might otherwise only start spawning much later.



Locked medicine crate
This locked crate is guaranteed to drop a large medicine, that will increase the player's maximum health.



Locked shield crate
This locked crate is guaranteed to drop a multiplie shields, that will give the player front armor.



Key
Keys can be found by killing elite enemies. Elite enemies are not guaranteed to drop a key, because there can be multiple elite enemies in a stage, with the exception of the first stage.

The key is usually not located in the same level as the crate. So if a crate is spawned in Level 2 of a stage the key will be found in Level 3 or Level 1 of the same stage.

There is a red key, a green key and a blue key. The game also knows other colors, but because every stage maps to one color and one crate with one key only the aforementioned three colors can actually be found.

Trivia
Destroying a locked crate before moving on to following levels will cause it to respawn in the following level. This is the only way to make it spawn in boss levels. This is useful if you want a different type of locked crate, because respawning will reroll the type.

You can move on without opening a locked weapon crate and only open it after reaching B-Levels to make it spawn better weapons.