It’s TJWhale here again to talk about realism and Thrive and sort out some common misconceptions.
What do we mean when we say Realism?
What we mean is that a proposed feature is within the laws of physics and chemistry as they are currently understood. So having an object which can travel faster than the speed of light is not realistic, because that violates relativity. However for the space stage there are several cool ideas for things which don’t exist now, but could exist inside the known laws of physics, such as Alcubierre drives or Wormholes which would allow FTL travel.
This means that if something exists on earth then it’s fine to be in Thrive because we know it must fit inside the laws of physics and chemistry in order to exist. However just because something doesn’t exist on earth doesn’t mean it shouldn’t be in Thrive. For example purple chloroplasts or a humanoid with six eyes are both fine because there is no principle reason why they couldn’t exist.
Does this mean that anything which is realistic can be in the game?
No, it’s not sufficient to say “this is realistic and therefore it should be included” because the whole point of making a game is to make it fun. Games are toys and are meant to be played with. Maybe “fun” is too small of a word, maybe the concept should encompass things like engagement, enjoyment, immersion, experiences that elicit emotion. There is no way to finish the sentence “it’s not fun but …” which makes it worth adding to the game.
For example if we were to consider making a slug simulator where it took 30 minutes to slither down a garden path this would be very realistic and very boring. Reality is awesome at times and can also be nasty, boring and dull. If we were to have something like this we would want to work out how to make this a cool experience (speed up the slug or speed up time or make a lot of tiny obstacles or something).
What does this mean for the microbe stage?
One thing it means for the microbe stage is that in general it’s fine to mix and match organelles between cells. For example a pilus is a structure found on Earth on bacteria so is it ok that in the game you might put it on a eukaryote? Yes, there is no physical reason why, on a hypothetical alien planet things won’t evolve like that. Likewise nitrogen fixation is believed to be restricted to prokaryotes but it’s not inconceivable for a eukaryote to have evolved that ability. Nitrogen fixation is being added to 0.4.0 and a nitrogen fixing plastid has been added to enable eukaryotes to fix nitrogen if they so choose.
There are some restrictions that will be imposed. For example prokaryotes won’t be able to have membrane bound organelles (like mitochondria, chloroplasts and chemoplasts) because you must have a nucleus to have membrane bound organelles. Moreover there may be other restrictions we impose down the line for gameplay reasons. However in general you should be able to take any organelle (eyespot or agent gland or bioluminescent proteins) and put them on any cell because there is no principle reason to disallow this. Moreover we are adding photosynthetic proteins which can be used by prokarytoes to do photosynthesis which are not membrane bound.
To summarise realism doesn’t mean “earth like” it means built with respect for the scientific laws as they are currently understood. There’s plenty of crazy stuff on Earth to prove that there is a lot of room in these laws, for example the largest prokaryotes are visible to the naked eye being 0.1-0.3mm in size. In 0.4.0 prokaryotes have been added to the game and they can grow to any size. Moreover there are cells which live deep in the sediment at the bottom of the ocean for thousands or millions of years in total darkness and extreme slow motion. We are also adding a cave biome which, like Movile Cave, will be pitch black and full of hydrogen sulfide. These caves can contain a whole ecosystem based on a different energy source.
At the moment we have plenty of inspiration for organelles which exist on Earth and we may choose in the future, depending on gameplay testing, to add more which don’t exist on Earth but could on an alien planet. That’s what makes Thrive a xenobiology game about hypothetical life.