Shapes that block sightlines / offer protection in combat-based games
Cover is any object or structure that blocks a sightline, shielding someone from a ranged attack. It is a common feature in any arena or encounter.
Half cover is a waist-height shape like tables, counters, sandbags, or windows. Defenders can stand and see over it, crouch behind it, or even jump over it. Because it is shorter, players must stay close to the cover, otherwise their head might be exposed.
In many games, crouching limits mobility, and so half cover makes players stay in-place longer and commit to a position. The excitement of projectiles flying overhead can also evoke an immersive war fantasy, popular in military realism games.
(half cover diagram)
Full cover is a standing height shape like a wall, pillar, or column. Defenders can safely stand tall behind it, and then sidestep outwards to peek out or return fire. Because players can stay on their feet, full cover is usually more flexible and stronger for a defender.
The height is important. It means defenders can stand behind it at a distance while still being protected. Taller cover also reduces an attacker's elevation advantage.
(full cover diagram)
Soft cover is thin or non-solid cover that offers little protection from fire but acts more like a visual screen to obscure the defender, like cloth, foliage, or water. Yet it also offers options for a defender, who can freely move through the cover for an ambush or surprise attack.
Stealth games often let players sneak through grassy fields, a form of soft half cover. But there's also a lot of risk, because if enemies detect the player then the grass will offer no protection from attack.
(soft cover diagram / examples)
Hard cover is thick solid cover that offers complete protection from any attack, yet also blocks any movement through it. Most cover is hard cover.
Sometimes even hard cover is not quite hard enough. In military realism games with bullet penetration mechanics, wood panels or metal sheets can leave the defender vulnerable if an attacker knows they can shoot through the thin object. (In Counter-Strike, shooting someone through a wall is called "wallbanging.")
(hard cover diagram / examples)
Free standing cover (or free cover) is a shape that fighters can move around easily. It usually favors the defender because it gives them more options if attackers overrun their position.
In particular, free standing full cover often results in players spinning around them, especially during 1v1 duels as fighters "dance" to keep the cover between them until they're ready to attack. A narrower pillar forces a closer faster dance than a wide pillar.
(free cover diagram)
Directional cover is a shape that offers effective protection only from a certain approach or trajectory. It usually limits the defender's options and leaves them vulnerable if an attacker comes from a different direction.
This type of cover is very common in single player / PvE design, where a player must solve an encounter by approaching enemies from their most vulnerable direction, which is rarely straightforward.
In team-based multiplayer games, directional cover offers an incentive for teamwork. A teammate can use directional cover to gain a strong position over one angle, while another teammate can defend their back to prevent attackers from flanking them.
(directional cover examples)
Shallow cover is when there is not much space for a defender.
Deep cover offers a lot of space for a defender.
(TODO: add more)
A trench is a form of vertical cover that sinks down into the ground, usually deep enough for full cover. Defenders pop their head over the top to see anything or return fire, but because it's so deep they cannot easily jump out over the top. Attackers must rush across a no man's land and then descend into the trench, which leaves them vulnerable from other ends of the trench / as well as additional lines of parallel trenches.
Only particularly perverse military shooters tend to replicate trench warfare patterns. As militaries in World War I discovered, entrenched defenders with machine guns have a very strong advantage against infantry; but as militaries in World War II discovered, armored tanks / combined arms make trenches dangerous for defenders. Either way, trenches often feel unbalanced and "not fun."
Elevation is vertical cover that raises a defender up, weakening half cover below while also limiting any attacker's approach to any ramps / stairways / lifts / jump pads / etc.
Even a simple platform with no walls can offer effective cover and sightlines, as long as the attacker stays at a steep angle. This type of height advantage is especially powerful in console shooters where gamepad users rarely change their vertical aim. People rarely look up.
To balance the height advantage, elevated cover often needs weaknesses built into it. You can make it soft, shallow, and/or directional, with few resources or utility for the defender.
(elevated cover example)
slice the pie, corners
Cover boxes are bad, thinking solely in terms of cover results in boring warehouse arenas
- "Judge A Map By Its Cover" by Andrew Yoder is an analysis of Counter-Strike: Global Offensive's most popular map de_dust2, specifically its cover patterns and sightlines. A lot of the ideas and examples from this page come from Yoder's post.