Terrains are categories for different types of land ranging from deserts and forests to bogs and tundra. Presented here are the classification for terrains, and what hazards and effects would be present in the terrain.
Dangerous to most creatures primarily due to most being unable to breathe within aquatic terrains. While underwater creatures are considered to have Total Concealment against creatures above water unless the water is completely clear, instead only granting them regular Concealment. While underwater ranged weapon attacks are impossible to perform unless otherwise specified, and in addition to this thrown weapons thrown into water are ineffective if they must travel 1 square or more downwards into the water to hit its target.
Spells can be cast normally while in water however the Stamina cost for doin so is increased by 4. In addition to this, attacks being made while underwater cost an additional 4 Stamina to perform unless you possess a Swim speed (ex. from a special ability or your species), or otherwise specified. Slashing and bludgeoning manufactured weapons only deal half damage underwater meanwhile natural attacks and manufactured piercing attacks deal damage normally (however all attack rolls underwater with manufactured weapons suffer a -5 penalty on attack rolls).
Where the water meets the land, beaches have sandy or rocky shores with little to no vegetation.
Sand in beaches are rarely trouble to traverse through, however the sand still not ideal as far as a combat terrain is concerned. Attempting to run or charge requires a DC 25 Balance check or you fall prone at the end of the movement (and in the case of a charge to attack, are unable to finish the attack).
Covering bogs, marshes, and swamps alike, boggy terrain is often difficult to traverse through with its combination of hazards and dreadfully poor terrain.
Attempting to hide while in a boggy terrain is easy, gaining a +10 bonus to Hide checks to do so, however the splashing of water makes Silence difficult at a -10 instead. In addition to this, attempts at using Smell take a -5 if the one attempting to smell isn't native to swamps (up to GM's discretion).
In these terrains there is the ever-present threat of quicksand or similar patches of loose sand. This functions as the Quicksand hazard. Spotting these without deliberately searching and combing the terrain for it requires a DC 35 Sight check.
Deserts are incredibly harsh terrains due to the heat and the abundance of sand in the surrounding area. Deserts are difficult terrain for those unaccustomed to traversing through it, and impose a -10 penalty to Balance, Dance, Jump, Sprint, and Tumble checks being made in the desert.
Desert terrains are often under the effects of heat (above 90 F) and in more extreme areas severe heat (above 140 F), however creatures and beings adapted to the desert are often able to overcome this heat or find ways to mitigate its danger.
Hiding is much more difficult in desert terrains due to the lack of obstacles which could allow one to hide behind. Unless through elevation or an obstruction, you're unable to make Hide checks in the desert normally without completely burying yourself (a long process which poses more risks than benefits).
Lastly, heat haze is a common occurrence in the desert, making those outside of a certain distance start to appear distorted and shimmer. During heat haze creatures have concealment against other creatures who are more than 6 squares away from them.
Forested terrain includes other kinds of woodland terrains like jungles, and isn't exclusive to just forests.
Standing in a square within a forest which is also occupied by a tree provides partial cover to the player. If the tree instead takes up the whole square they cannot stand in it but can instead use the tree like a wall (thus completely blocking line of sight).
Being able to hide is much easier in these heavily forested areas, granting a +10 bonus to Hide checks attempted within the forest.
Hilly terrain includes gentle and rugged hills which serve as a transition between even terrain and mountains.
Due to their steepness, travelling uphill takes 2 squares of movement to do while travelling downhill requires a DC 20 Balance check and on a success you travel 2 additional squares if you move more than 2 squares during your land movement. On a failed Balance check you instead fall prone in the square you were about to step into.
Attacking enemies who are downhill from you is easier, and you receive a +2 bonus to attack rolls against them.
Mountainous terrain includes alpine meadows, rugged mountains, and forbidding mountains, separated typically by height (alpine meadows leading into rugged mountains and finally forbidding mountains at the summit).
Mountains function as Hills for the purpose of moving uphill and downhill, except the Balance DC for going downhill is 28 instead.
Some mountains possess chasms which are similar to pits, ranging in deepness between 4 squares and 16 squares.
Plains terrain are typically flat, and have very little in the way of dense foliage.
Some plains areas are dug for battle, including trenches or berms. These provide cover to those attempting to use them.
Urban terrains are mostly comprised of streets and buildings such as houses and shops.
City walls are typically made with smooth stone which requires a DC 60 Climb check in order to traverse, and such walls are usually 4 squares tall and 1 square thick.