I have been putting together a homebrew star system to be used as another star system in the Starfinder Setting. I have written a bunch on paper and decided to start typing it here to get feedback. :D
Let's start with planets.
The closest planet to the sun is known as Asawa. It is a desert planet with temperatures ranging from 150 degrees Fahrenheit during the day to 60 degrees Fahrenheit at night. It has sustained wind speed of 15-25 mph with gusts of 40mph very common. It currently has no native life but it does possess many ruins. Using carbon dating it appears that the race known as the varcoids built cities here from 13,000 PG to 3,000 PG but the other races in the system had no contact with them. The varcoids were an advanced race, with powerful gravitational technology, but it appears like they never made it off Asawa.
The second planet, and arguably the most important one, is Vilan. Vilan's surface is covered with oceans, which make up 73% of the planets surface. Vilan has high levels of rainfall and it is teeming with jungles,.forests, and grasslands. The dominant species here is the aradans, a turtle like race that lives above and below the water. The aradans share the oceans with both merfolk and Triton's and mantain good relations with both. The aradans are naturally friendly and slow to anger, but they never forgive. Aradans have 4 sexes, but no concept of gender, and are sexually quadmorphic (?). Vilan has two moons, Memz and Ara.
An asteroid field. A whole lot of sincan and drasathian mining.
A gas giant. Some gas mining. Nothing is really here. A whole bunch of moons.
One of Centi's moons, Ko-Ash is home to two different sentient species. The planet has an incredibly active geology, and the core is connected to bother the plane of fire and the plane of earth. It is mountainous and water only covers about 20% of the surface. The two species living here are known as the sincans and the drasathians. Thanks sincans are a small race with no eyes. Instead their skin both captures and creates photons, allowing them to see in all directions, as well as emit light. This serves them well in lightless caves. They live in caves and the deep crevices here. They are insular and typically live alone. The drasathians, however, live outdoors. They have tall, little bodies, and possess incredibly strong and fast blood clots. This helps them to recover from long falls. They are a traditionalist people, with a love for climbing. The drasathians and sincans share the planet with magma elementals and frost, fire, stone, and slag Giants. The sincans and drasathians hate each other and recently fought an 119 standard year war over both Trassel Belt territory and territory on Ko-Ash. Neither side won, and instead it was ended in 272 AG by aradan peacekeepers.
An ice planet with lots of caves but no life.
Now time for races.
I already wrote some thematic stuff so this is just stats.
+2 Con, +2 Cha, -2 Wis.
Aradans are tough and friendly but tend to be impulsive and short sighted.
Size and Type
Aradans are medium humanoids with the reptilian, aquatic, and aradan subtypes.
Aradans can breathe both air and water and have a swim speed of 30 feet.
Aradans possess a tough she'll and gain a +1 bonus to KAC. In addition, an aradan can enter their shell as a move action. While in their shell they can't take movement based actions (GM decides) except to exit their shell as a move action. While in their shell an aradan gains a +4 bonus to KAC instead of the +1 bonus. They are also considered prone.
Sexually Quadmorphic (not sure if that is a word)
Aradans have four distinct sexes.
Lamau: +10 base speed
Remau: +2 bonus to Str
Tikau: +2 bonus to Dex
Nokau: KAC bonuses from shell increase by +2
+2 Dex, +2 Wis, -2 Cha
Sicans are fast and wise but don't understand other people.
Size and Type
Sincans are small humanoids with the sincans subtype
Sincans' skin naturally captures photons, and emits some of its own. A sincans has all-around vision (can't be flanked) and increases the light level around them by 1 to a range of 30 ft. This light can be turned off and on as a swift action.
Sincans naturally live in caves and have a +2 bonus to perception checks.
Once per day as a standard action, a sincans can shine intense light. This emits bright light in a 30 ft radius, normal light in a 60 foot radius, and dim light in an 120 ft radius. This lasts for 1 minute per character level, but can be cut short as a swift action, but if cut short it is lost for the rest of the day.
+2 Con, +2 Wis, -2 Int
Drasathians are tough and have learned much from tradition, but struggle with harder concepts.
Drasathian blood clots extraordinarily fast, and makes extremely hard scabs. Whenever a drasathian is reduced to an increment of 1/4 of their HP (but not SP, excluding 100%) they gain a +1 bonus to KAC and DR 1/Adamantine. The DR stacks with itself but nothing else while the KAC bonus stacks with everything. A drasathian is immune to bleed damage.
Drasathians can see up to 60ft in the dark.
A drasathian gains a +2 racial bonus to athletics
Merfolk (from Pathfinder)
+2 Dex, +2 Con, +2 Cha
Merfolk are graceful, half, and beautiful.
Size and Type
Merfolk are medium humanoids with the aquatic subtype
Merfolk are accomplished swimmers and have a swim speed of 50 feet and are amphibious, but only have a base speed of 5ft.
Merfolk have a +2 bonus to KAC because of their tough skin
Merfolk can see as well in dim light as they can in normal light.
That's all for now, but I have way more lore, weapons, armor, and feats to share. What do you guys think? All criticism is welcomed.