Red Rock Valley
The Red Rock Valley is land in HyperRogue. It is unlocked by collecting 60 global treasure, and 10 spice. The monsters include Red Trolls, which move like the player, and Rock Snakes, which are similar to Sandworms, but they move every turn, and cannot pass through heptagons.
The land itself consists of tiles with 4 height levels: ground level and 3 levels of red rock above that. The player can only move to a tile at most 1 height level above the current tile, or to a tile at most 2 levels below the current tile. Climbing more than 1 height level is prohibited, as is dropping more than 2 height levels.
Initially, the land consists of mostly ground level tiles with islands of level 3 tiles. Treasure is spawned only on level 3 tiles. In order to reach the treasure, the player has to kill the Red Trolls and Rock Snakes. Each time a Red Troll is killed, the tile it's standing on increases in height by 1, up to a maximum of 3. Each time a Rock Snake is killed, its head adds 1 level to the current tile, and the rest of its body adds 2 levels.
Strategies
Apparently the safest approach is to avoid the fast-moving Rock Snakes altogether and lure the Red Trolls next to the level 3 islands, killing them in a way that builds a "staircase" up to level 3. However, this is generally very difficult to execute, because by the time the trolls are lured to the right positions, a Rock Snake or two will also be incoming, making it very hard to retrieve the treasure and get back down safely.
A more effective approach is to kill a Rock Snake. This immediately creates an entire row of height 2 tiles, with a height 1 tile at the head that can be used for climbing up. Any part of the Rock Snake that was next to a height 3 island can now be used to reach the treasure. Since Rock Snakes are prohibited from moving on heptagons, this is actually easier than it appears. A rather effective approach is to find a narrow corridor between two islands with a heptagon and lure a Rock Snake in after you. Step off the heptagon once it reaches you, and it will be unable to move.
Once a Rock Snake is killed, climb onto the level 2 tiles its body created as a high ground from which more Red Trolls and Rock Snakes can be killed. Since monsters also cannot climb more than 1 height level at a time, it's harder for them to reach you if you retreat to other parts of the high ground, so this is a more advantageous position. Once this position is obtained, it can be used to trap and kill more Rock Snakes, creating more level 2 tiles, eventually forming a level 2 elevated plateau from which it's easy to reach treasure. Beware, however, that killing trolls may leave step ladders that allow monsters to climb onto the plateau. If this happens, it's probably wise to abandon it quickly, since a Rock Snake moving on level 2 tiles can easily corner you.
- See also: Red Rock Valley Illustrated Strategy