This is a fairly straightforward idea:
In early games of Sim City desktop series, when you created a new map, you were able to choose which edges of your map would have beaches, you could have a river going through your map going vertically or horizontally, and you could choose to have a lake in the center of the map. This was chosen simply by clicking any combination of 7 buttons, 4 of which represented each edge of the map, 2 to represent the river buttons, and one of which represents a lake in the center. the latter three buttons would only allow one or no selection, but you could select all 4 of the first 4 buttons if you choose.
For example, choosing the north and west edge would make it so that the north and west edges of your map end in ocean. In those games, you could use this to make island with a lake, two islands(due to the river-like body of water splitting one island into two.), a peninsula, or even just a regular one-sided beach map.
I think that this would be useful in creating a new my colony map, for any planet, because it would allow you to choose what kind of land formation you want to build on and you can choose how difficult or easy the map is based on how much land will be available for you to build on. To make things interesting, I would keep the random generation, but I would alter it to adhere to the customizer, so while bodies of water would still be randomly generated, they would be limited to the customization choices of the player. For instance, if the player chooses to have a regular island with nothing in the center and water on all sides, he shouldn't just get a square island with square beaches, but the edges of the island should be smooth and natural looking, and a random generator can be tuned to perform this very task. This way, every time you make an island map, it's going to be a completely different shape every time, unless the game happens to use the same seed, which is so rare that it would be like rolling a million dice and having all of them land on the same number.
I also think that this could be applied to all worlds, except lava world at this point in time. Red planet could have ice tiles that resemble frozen oceans, which rovers and colonists can walk on and buildings can be placed on. However, once the planet has enough atmosphere, that ice turns into water, and anything on the ice tiles that can't fly or swim will be destroyed. I would also like to see earth-like water bodies come to forest, abandoned world and sugarland, and I would like to see the ice world gain the same ice bodies as mars. I also want to see that ice world is terraformable but I've never gotten that far into an ice world to see if it is or not. Lunar could also have formations that indicate where water would form when the planet is terraformed. I really wish bast would go all-out with this, because these ideas would definitely be worth it, at least to me.
Now, regarding my sea level/water level resource idea. I think that my colony would benefit from a statistic or resource that detirmines how much of the map is covered in water at any given time and whether more or less tiles should be covered from one second to another. Maybe in the near future bast can consider throwing out his randomly generated rivers for a tile elevation system. If he wants to keep things 2d and doesn't want to add textures that pop up out of the tiles and act like mountains, cliffs, or sorelines, he can simply create a random generator and tune it to make a random topography of the map and assign each tile an elevation value based on the customizations chosen by the player before creating the map. When the water level becomes more than a tile's elevation value, that tile turns into water and every non-amphibious unit/structure on that tile is destroyed. I would have the tile turn from normal ground into sand before it turns into water just to warn the player of the rising sea level, and to ensure that the bodies of water are surrounded by sand.
This would also allow for multiple new structures for each raced to be added to the game that have a direct correlation to sea level. You could have buildings that rise and lower the sea level so you can get the desired sea level. Certain buldings could also remove and add to the sea level as a side effect as well, such as the atmosphere condensor, which would add a little bit to sea level, or the basic water pump, wet mound, or wet cone could remove a little bit from sea level turn to them drawing water out of the ground. once the sea level is completely at 0, with the exception of the water pump, the wet mound and cone don't work.
This water level feature can also determine the overall dryness of a planet. If the planet is too dry, colonists will sleep during the day and work at night to avoid dehydration, and they would consume more water and produce less food, and you could have dust devils or sandstorms that do damage to buildings. If the planet is too wet, colonists would get sick because many diseases lurk in moist environments, but they would produce more food and use less water, and you could have monsoons that greatly and suddenly increase the sea level for a short time. This factor would play a key role in terraforming dessert and ocean planets in case you were thinking about adding those. Imagine starting out on a small island surrounded but a vast ocean. In order to get more land though, you must put your space saving skills to the ultimate test and work toward lowering the sea level and eventually freeing up more land.