Following on from this discussion, a set of icons for various in-game elements need to be decided upon and created. Off the top of my head, the categories are biomes, compounds and organelles, but if I've missed anything you think should have a dedicated icon set tell me.
In general, the icons need to be small, simplistic, distinctive, representative and coloured differently. Think the beakers, coins, resource icons, etc. from Civ V, or the system icons from FTL.
We don't really have a proper list of biomes. We have my initial suggestions, this thread and a thread on the community forums, which, not to be mean, can probably be 90% discounted just because they got a bit too fantastical and nuanced for what was required. For instance, blood stream is a no-go since you'll be evolving long before any complex life has appeared. I will pick some of my favourite suggestions for the list below though, and if any devs think any others have merit we can add them too. In my opinion there were quite a few good ideas that ended up being too similar to one another. Anything volcanic, for instance, can be incorporated into hydrothermal vents.
Biome icons don't need to have a single colour since they aren't tied to any concrete in-game visuals (as compounds are, as I'll explain later). In my opinion they should probably all be circular and filled with a simple image representing that biome. If anyone has any better or additional suggestions, say so below.
- Hydrothermal vent - Heavily red with some grey and orange. The design should probably be an underwater volcanic vent, like this but coloured to make it distinctive and fit the biome's visuals.
- Shallow ocean - An image of the ocean meeting a beach should do, predominantly light blue, white and yellow. Something like this.
- Tidepool - I'm going to go back on my choices for tidepool colouration from the biome visuals thread based on images like this. In my opinion the icon should show a rocky perimeter and focus on sandstone reds and oceanic greens.
- Cyanobacterial mat - Very green, showing a layer of bacteria. Use these sorts of images for inspiration.
- Abyss - Minimalist black and dark blue, like this image.
- Glacial melt - White and blue, with an icon showing a glacier or icy water. It's not hard to imagine, but I'll include an image here anyway.
- Petri dish - Although it would never appear in the environment, I quite like the idea of a petri dish as the "testing" area in the editor. I'm struggling to think how it could be represented besides an image of an actual petri dish, with very little colour saturation.
- Tectonic water fill - Browns and oranges, close in style to this.
Compounds are probably the most in need of dedicated icons, since we want the player to know at a glance what compound they're dealing with. Compound icons in particular are important because they'll accompany compound clouds, coloured distinctively in the environment for the same purpose. We decided on the colours for each compound currently planned, so all that remains is to create icons using those colours. Unlike the biomes, I think compound icons should have their own distinctive shape.
- Glucose - White. The icon itself is difficult, since there isn't a universally acknowledged symbol for glucose beyond its chemical structure, which is far too complex to present to the player. Instead, I'm thinking either a hexagonal ring or a sugar cube.
- Amino acids - Pinkish red. Another annoying one for the icon itself. We could use simplified DNA, but my understanding is that would be the icon for Mutation Points. I put angular chains in the GDD appendix for compounds, but that was little more than a guess.
- Proteins - Darkish red. The easiest thing to have represent protein is a stylised steak or slab of meat.
- Ammonia - Yellow. Again, really quite difficult to think of a well-known symbol for ammonia. If necessary we could go with four circles arranged in the pattern of its chemical structure, since it's quite distinctive and far simpler than most of these in chemical structure.
- Oxygen - Light blue. Bubbles?
- Carbon dioxide - Dark blue. Not sure, but one possible option is a cloud since most people are familiar with it as a greenhouse gas.
- ATP - ATP doesn't appear as a cloud in the environment but it'll still need a colour and icon. I'm thinking a green lightning bolt.
- Water - The icon is probably the most obvious of them all: a water droplet. Colour is more difficult, since water won't appear as a compound cloud and can instead be thought of as transparent. Transparent icons aren't possible though, so what do we do here?
- Hydrogen - A colour wasn't decided on in the thread, but I'll propose orange. And a flame for the icon.
- Calcium - Beige probably. A stylised bone for the icon.
- Nitrogen - Nitrogen's colour was never decided on and all types of blue are already taken. I don't know for this one.
Since organelles are represented by in-game entities as compounds are, their icons should ideally match the general colour of the organelle model. The problem is distinguishing organelle and compound icons. One solution would be to have a set format for all organelle icons, such as a circle with a vector drawing of an organelle in the centre. To distinguish them chromatically, we could have organelle icons consist of two colours each, maybe even two colours related to the compounds they process. This becomes a problem for non-processing organelles though (like pili, flagella and cilia).
Perhaps a better solution is to have every organelle icon be the same colour but keep their shapes as distinctive as possible. For some, this is easy - a flagella can hardly be mistaken for a nucleus. Others might be more difficult - how can you differentiate the golgi apparatus and endoplasmic reticulum by shape alone?