3
moons
|
3
space-constructs
|
2
death
|
2
sports
|
3
mechs
|
3
universe
|
2
demons
|
2
social-media
|
3
magnetism
|
3
wheels
|
2
dream
|
2
secret-society
|
3
futurology
|
2
cloning
× 3 |
2
climate-change
|
2
prehistoric-times
|
3
generation-ships
|
2
ecology
× 2 |
2
black-holes
|
1
radio
× 2 |
3
industrial-age
|
2
government
× 2 |
2
asteroids
|
1
alternate-history
× 2 |
3
colonies
|
2
map-making
× 2 |
2
aircraft
|
1
language
× 2 |
3
alien-geometry
|
2
kaiju
|
2
airships
|
1
macroengineering
|
3
assassination
|
2
mind
|
2
alternate-earth
|
1
light
|
3
cities
|
2
mind-control
|
2
venus
|
1
merfolk
|
3
bronze-age
|
2
gender
|
2
vikings
|
1
natural-growth
|
3
slower-than-light
|
2
intelligence
|
2
virtual-reality
|
1
hive
|
3
tectonics
|
2
control
|
2
spells
|
1
bio-mechanics
|
Shadowzee
