I think we need to add some kind of weighting value to each parameter of the formula posted earlier in this thread.
So far the results i've been getting are rather disappointing.
The most habitable planet i've seen listed on this forum is RS 1137-1-5-26728-4 6. This planet scores around 40% and I didn't even bother taking into account the presence of a moon. The formula is rather punishing when you apply it on the property of the mass of a planet. The range of planets that should score higher results should be wider in my opinion.
Looking at the mass parameter alone, Mars scores 0,39.
That in itself is not unacceptable. But if you compare with the results you get when you apply the formula on the temperature property, almost all of the planets other users have posted on this forum, scores +0,90. Many of these planets would by extremely hot or cold for us.

We should define a range of acceptable values for each planetary property, and adjust the formula, perhabs using a weighting value, to have the fomula go off the chart, when you fill in values outside that defined range

Maybe in next release I include calculation of Earth similarity index based on some equation. It will be displayed in planet info table. I don't like the standart ESI formula - it has extra data. Raduis and surface gravity is equivalent to radius and escape velocity or radius and bulk density. I prefer atmosphere pressure instead of bulk density, and surface gravity instead of escape velocity. Of course, the parameters were chosen for real exoplanets because we have no data about atmospheres, but temperature together with escape velocity gives an idea of what gases can be hold by planet.

The ship could have a short of scan device /telescope with spectrometer) which would allow for scanning of nearby system e.g scan in all directions within an "x" light year radious for planets with ESI 0.9 or higher. If there is an economic system ala Elite/Freelancer/Evochron etc, the more money you earn from your adventures, the better scanners you will be able to equip your ship with, so that you can scan 2x light years or more radius and with more accuracy

This breaks the gameplay. If anyone has such "scanners", nobody will take a journey. Any interstellar flight will be just a business trip. And I don't believe that it is possible to detect life from 2 ly. You should take a year of observation on modern telescopes to detect a few spectral lines from a planet. To see Earth-sized planet disk from 2 ly as image with 10 pixels radius, you should use the telescope with an aperture of 10 km! Anyway, observation takes a lot of time. It is much faster to fly to that system and visit every planet

Is this challenge still on?

I have Found a good candidate on the edge of the galaxy, but I think there is something wrong with my 'sensors' because a planet on this orbit should never be this cold. The presence of liquid water confirms that my sensors need a "level 1 diagnostics" smile

I think the 3 most important parameters should be:
1. Gravity (mass/volume depended)
2. Temperature
3. Atmospheric Pressure

There should be minimum deviation from earth's values for these 3 parameters. Advanced Life i.e. complex life forms - not just bacteria and amoeba, has very low tolerance in variations of these parameters. There must be a constant which can be applied in the equation that will increase the impact these parametrs have on the similarity index.

This candidate looks not so bad. Fairly short days but we could live there:D

This candidate looks not so bad. Fairly short days but we could live there:D