rewrite the sentence starting with “All islands have a score for Land” to:

All Islands have a topology, which is a list of levels. A level is an integer number, and may be referred to by its position in the list. The default value for Topology is a single level with 5 land. An island’s Land is the sum of the Levels in its topology. If an island’s land is increased without specifying which level is increased, the first level of its topology is increased.

Change:As an Optional Action, an Island in a Receeding Sea may increase its level by 1, adjusting its Land value accordingly.
To:

As an Optional Action, an Island in a Receeding Sea may add a new level with 0 land to the beginning of its topology.

Change:“If in a Receding Sea, increase their Level by 1 (adjusting their Land value accordingly).”
To:

If in a Receding Sea, add a new level with 0 land to the beginning of their topology

Change:“Each Island has an Altitude statistic which is measured in Levels. Altitude must be a positive integer, defaulting to Level 1, and tracked in the Great Sea page of the wiki.”
To:

Each Island has an Altitude statistic, which is the number of levels in its topology.

change: If an island’s foliage would be set higher than an island’s Level, it is instead set equal to the island’s level
to:

If an island’s foliage would be set higher than an island’s land, it is instead set equal to the island’s land