It has been some time since the last update. We have had quite some work to do, and have now decided to roll out a first version of our new simulation mode, involving water chemistry!

Some notes to get you transitioned:
When executing Behind Glass, you will now get a launch screen, letting you choose between different save games, and letting you start a new game in two different sandbox modes:
Designer -- this is what you know until now, our aquascaping tool, letting you create your favorite tanks! Your previous game session is running in this mode.
Simulator -- this is the new simulation mode, involving water chemistry. Please note that the current state is just the beginning of this new mode, so expect improvements and additions over time! The simulation mode is currently intended for "aquarists knowing what they need to do" -- there is no tutorial and no extensive documentation as of now.

Some notes about the simulation mode:
There is no need to place deco/background/gravel coverings in simulation mode: algae will grow automatically once it finds the right conditions.
After you have placed a fish or a plant in your tank, you cannot alter their size anymore: fish and plants will grow automatically.
Most simulation-related information is shown in the new simulation window.
In the simulation window, you can add filters, dosing pumps, heaters, chillers, water changers, oxygen sources, and carbon dioxide sources to your tank, and configure these equipments individually.
In the simulation window (but also in the main HUD), you can jump a day or a week to the future at any time -- this is where the actual simulation takes place, altering your water parameters, as well as your tank and its contents.
In the simulation window, you can view various water parameters and their historical changes, either individually or in fixed/self-defined parameter groups.
We have currently integrated a variety of water parameters. We obviously cannot model all aspects of water chemistry, so please kindly tell us if you think some missing parameters are of utmost importance.
Parameters currently modeled are (depending on water type): PH, Carbonate Hardness, General Hardness, Oxygen, Carbon Dioxide, Ammonia, Nitrite, Nitrate, Surface Motion, Organic Waste, Effective Light, Nitrobacter Bacteria, Nitrosomonas Bacteria, Denitrifying Bacteria, Tannins, Salinity, Chlorine, Chloramine, Green Algae, Coralline Algae, Calcium, and Magnesium.
Concepts that are currently modeled, among others, are: nitrogen cycle with three kinds of bacteria, two types of algae, KH/CO2/PH relationship, black water due to tannins, lighting, coral calcification, fish and plant growth, impact of surface motion on aeration, and impact of various chemicals.
Fish and plants require species-depended water parameters to thrive. They will become stressed if their requirements are not met. You can see this stress in their appearance -- they might even swim on their back if fully stressed. But no worries: if the stress disappears, they will become healthy again.
As in real life, it might be impossible to keep different species happily together, as they have opposing ranges of, e.g., PH, they can cope with.
The already known fish and plants info window (clicking on fish/plants before placing them in a tank, or clicking on the (i) after having placed them) now additionally contains details on fish/plant requirements and their potential/current stress. There are also new fish/plant overview windows, featuring lists of all fish/plants, their requirements, and current condition.
What is your goal in simulation mode? Simulation mode is currently a sandbox (as is designer mode). So your goal is to create the tank of your dreams, that is well-balanced and keeps all its inhabitants happy.
What to do first? You need to get the nitrogen cycle running! This can be done by placing biological filters or decoration items being able to house bacteria, then put in lots of ammonia (or, in this simulation only, fish that will initially get stressed but eventually be fine again), and finally let the bacteria grow over some weeks. Afterwards, your water parameters should be fine again.

How can you help?
Let us know what you think about the new simulation mode! Did we miss something of utmost importance -- please let us know!
Are you a water chemistry expert or generally an aquarium expert, and are willing to help us improving? Please contact us!
We surely have some errors in, e.g., the requirements of certain fish species. If you spot some mistakes, please tell us, so we can fix them!

Other news:
You can now delete fish and deco with the delete/backspace key. The HUD opener in the lower right auto-hides after some time.
We have added 10 new species: Boeseman's rainbowfish, Firemouth cichlid, Fiveband barb, Humphead cichlid, Lagoon triggerfish, Old wife, Orange skunk clownfish, Silver dollar, Threadfin pearl perch, White-freckled surgeonfish.