Codename: Loop automatically generates navmesh for the map, which gives the Monster AI better pathfinding and also eliminates the need to place info_nodes on the map.
Any solid entity with its Render Mode set to "Texture" and its FX Amount set to 255 will be treated as solid but will ignore projectile collisions, meaning, that you can create a "fence" or any "semi-solid" entity using only a func_wall.
Correct Trigger States
Almost all entities will obey trigger states correctly, which means that a func_door will open when receiving an input of "On" and will close when receiving an input of "Off", a func_train will start moving when receiving an input of "On" and will stop moving when receiving an input of "Off", etc...
In Codename: Loop you can perform stealth kills if you get behind an enemy undetected and use your crowbar. You need to approach the enemy while crouching, this way they can't hear you.
You can implement sections on your map that includes stealth to change the pacing of the game.
Inventory and Objective System
The Inventory system allows mappers to create a custom item (item_generic) that is stored in the player's inventory and can be used as a key to unlock certain entities. The inventory is displayed in the radial menu.
The Objective system allows mappers to define an objective (game_objective) and lock certain entities until the objective is completed. The objectives are also displayed in the HUD.
Codename: Loop includes a wad file "looptools.wad" which contains some special textures that you can use for mapping. The skip textures will turn any face invisible in-game, the other textures are needed to make some entities like func_clip and func_fade_zone work correctly.
Additionally, the AAATRIGGER texture should not be used, use the tool_trigger texture instead.