Tropical biome

Rust’s Deep Sea has a tropical look of its own: white sand, green grass and pale rock. Creator can give that look to your map in one of two ways, or not at all. Both are optional and both are off by default, so a map that never uses them is exactly the map it always was: Arid is desert, as it is on every Rust map.

Rust itself only knows five biomes and draws the whole world with one set of ground textures at a time. The tropical look is a second set of ground textures, and under it the lush tropical ground is the Arid column. That one fact explains everything below.

The two modes

The control has two checkboxes, and only one can be on at a time. Turning one on turns the other off; turning the one that is on off returns the map to plain Arid. You find the same control in three places, and they all set the same thing:

HELP, the MAP DATA tab, where the settings that belong to a map live
the Island Stamp panel (see Island Stamp)
Paint: Biome, under the Biome list

Each change is one step in the undo history.

Semi-Tropical

Semi-Tropical (paint where it applies) makes Tropical a sixth biome. It appears as the last entry in the Biome list of Paint: Biome and you paint it like any other biome. The Island Stamp also writes it under every island it stamps.

What each server shows:

Server	What a player sees on Tropical ground
Running the Creator server extension	Standing on Tropical ground, the tropical look: white sand, green grass, pale rock. Their whole view switches while they stand there, so any desert or snow they can see changes too, and it switches back when they leave. Everyone else keeps the ordinary look. See On a server running the extension.
Vanilla, no extension	The palms, rocks and other props you placed, on ordinary desert ground.
Either, seen from outside a Tropical area	Desert ground with the props on it.

Tropical ground is saved as Arid in the map’s own biome layer, because that is the ground the tropical look draws as lush. You never paint Arid for it: painting Tropical paints the Arid underneath in the same stroke, and painting any other biome over Tropical takes both away. The Tropical layer itself is saved in the map’s Creator data, which a vanilla server ignores and the extension reads.

Beaches in a Tropical area belong in Sand (slot 2), not in the Snow slot. From outside a Tropical area the Snow slot draws as snow, while Sand reads as desert sand from outside and white sand inside. The Island Stamp follows this rule for you.

Water-bounded or inland. A Tropical area can be an island, a peninsula behind a strait, or a patch inland. Water between the two looks hides the moment a player’s view switches; an inland edge shows it. Both are allowed.

In the editor, the ground under a Tropical area looks like desert, because the editor draws the same five biomes the game does. While Paint: Biome or the Island Stamp is active, a line in the Tropical color traces the edge of the painted area so you can see where it is.

On a server running the extension

When a map in Semi-Tropical mode loads, the extension reads the painted Tropical layer and then:

Checks every player about once a second. A player whose feet are on Tropical ground is switched to the tropical look. Only that player is told; nobody else on the server hears anything, and the server’s own setting stays at the ordinary look.
Leaves a margin at the edge. A player switches in as soon as they step onto Tropical ground, but switches back only once they are about 12 m clear of it, so walking along the border does not make the view flicker.
Handles joining and leaving. A player who joins while standing on Tropical ground gets the look as soon as they have finished loading in. A player who disconnects is simply forgotten, and gets the right look again when they come back. Unloading the extension returns every switched player to the ordinary look.
Tells the game’s own spawns the ground is Tropical. Spawns that look for the Deep Sea’s tropical ground, such as coconuts, can appear on Tropical ground, and spawns meant for one of the five ordinary biomes only treat it as that biome where it is not Tropical. A server plugin can ask the same thing: on Tropical ground, the game’s biome query for the Deep Sea biome answers yes.

A map in Fully Tropical mode, or with both modes off, is never switched per player: Fully Tropical is the one server setting shown below, for everyone at once.

The settings that control this, and the lines the server log shows, are on the server extension page.

Fully Tropical

Fully Tropical (the whole map) puts the whole map on the tropical ground textures, on any server. It needs no painted layer. The map asks the server for this line, and Creator saves it beside the map for a server without the extension (see Run your map on a server):

deepsea.terrain_everywhere true

What that changes, everywhere on the map:

Snow becomes sand. The tropical textures have no snow, so every snowfield draws as pale sand.
True desert is gone. Arid draws as the lush tropical ground.
Every ground texture except grass changes, including dirt, rock, forest floor, stones and gravel.

Arctic ground keeps a frosty tint on its rock and grass, so a painted Arctic area still reads as cold, but not as snow.

Switching modes on a painted map

The Tropical layer you painted is kept whatever the mode:

With Semi-Tropical off, it is saved and not applied, and the ground there saves as plain Arid. Turn Semi-Tropical back on and it returns.
With Fully Tropical on, it is saved and not used, since the whole map is tropical anyway.

The control tells you how many painted Tropical cells the map is keeping when the mode is not applying them.

What the check tells you

When Semi-Tropical is on, the map’s server-ready check adds notes. None of them stops the map from running:

Note	What it means
No ground is painted Tropical	Semi-Tropical is on, but nothing on the map will look tropical.
Needs the Creator server extension	A vanilla server shows only the props on Tropical ground.
Snow slot inside Tropical ground	Those cells draw as snow from outside the area. Repaint them with Sand (slot 2).
Inland edge	Part of the Tropical edge borders land, so players crossing there see their view switch.

Generating a Tropical map

In Creator Mode the Procedural Generation panel has a TROPICAL section with the same two checkboxes. Both are off by default, and with both off a run writes nothing tropical: Arid stays desert. A Standard Mode run never uses this section.

Semi-Tropical (the islands or area you choose) makes the chosen ground Tropical as the run finishes, then dresses it with the Deep Sea islands’ own plants and rocks (see Palettes below). You choose where in two ways, and you can use both:

Islands. On This map’s terrain, the section lists the islands the panel measured, largest first, by the same numbers the island list shows. Tick the ones to make Tropical. A ticked island is made Tropical whole, down to its waterline, and its ground is saved as Arid under the Tropical layer. Water around an island hides the moment a player’s view switches.
Inland area. The Arid band Rust’s own generation places makes the desert band the generator already made Tropical: every piece of land where Arid is at least half of the ground. The band keeps its own ground and its own soft edges; only its look changes. It is inland, so a player crossing its edge sees the view switch.

Beaches inside the Tropical area are moved from the Snow slot to Sand (slot 2), for the reason above.

Fully Tropical (the whole map) sets the whole map to the tropical look, as described above, and places the plants and rocks wherever Arid is the main biome, which is where the tropical look draws its lush ground.

Prop density is a percentage of what the Deep Sea islands themselves carry: at 100 % a Tropical area gets as many trees, bushes and rocks per square kilometer as those islands. Below the islands’ list the section shows what the chosen islands would get at that density. After a run, the last line says what the run did.

The TROPICAL section’s settings are saved in the map’s recipe and in presets, like every other Creator setting.

Palettes

The plants and rocks come in four palettes. Their default density is the density the four Deep Sea islands carry, measured from the islands themselves:

Palette	Default per square kilometer	What it holds
Trees	about 3,030	the islands’ palms, trumpet trees and strangler figs
Bushes	about 4,190	creosote, mormon tea and the islands’ overgrowth bushes
Rocks	about 1,580	the game’s arid rocks, sized and mixed like the islands’ own rocks
Clutter	none	tropical bushes, monstera and small tropical rocks

The islands place no clutter of their own, so Clutter is off by default; raise its density to use it. Each plant and rock only goes where the game itself would put it: never on a road, a river, a lake, a cliff or inside a monument, and the clutter follows the game’s own tropical ground rules (tropical bushes on grass, monstera at a forest edge, small rocks on stones and gravel).

The prop budget. One run or one placement adds at most 20,000 props. When a large area at a high density would ask for more, every palette is scaled down together, so the mix stays the islands’ own, and the readout says so.

In the Prefab Browser

The Prefab Browser has a TROPICAL tab with the four palettes and the ISLAND ART, the Deep Sea islands’ palms, rocks and cliffs as one prefab each (the Island Stamp places one with its ground). At the top of the tab:

Place over chooses The Tropical area (the painted Tropical ground while Semi-Tropical is on, or the Arid land while Fully Tropical is on) or Around the view, a circle around the point you are looking at, with its Radius (m). Around the view ignores the biome, since you chose the place.
Density (%) is the same percentage as above, and the line under it shows how many props the settings would place and whether the budget scales them down.
PLACE ALL PALETTES places all four; each palette’s own button (PLACE TREES, PLACE BUSHES and so on) places that palette alone.

Each placement is one step in the undo history. Inside a palette, click a prefab to preview it and double-click to place a single one, as on the other tabs.