The why of gangs

Criminal gangs are a hazard players are most likely to run across in city areas. They can be ambiguous - enemies or allies depending on how the first encounter shakes out.

Most gangs are money-making enterprises that see violence as a tool of the trade. Often, recruits join up to have protection from other gangs. It's common for gangs to claim a territory and keep order there by muscling out or co-opting other criminals.

This is a table to make gangs less generic by generating a background, operating methods and members. Roll as many times on any given table as you need to reach the preferred complexity.

Their members

1. Neighbourhood thugs
2. Disgruntled ex-soldiers
3. Guild dropouts - drunks, bullies and workshy
4. Long term jobless forced to choose between crime and begging
5. Branded criminals
6. Vigilantes

Their size

1. Less than ten
2. Ten to twenty
3. A few dozen
4. A hundred or so 
5. Many hundreds

Their methods

1. Smuggling
2. Gambling
3. Armed robbery
4. Protection
5. Bootlegging
6. Murder/arson for hire

Their 'reason'

1. Protect immigrant districts
2. Resist political oppression of the lower classes
3. Prevent exploitation of the poor by landowners
4. Stop locals being displaced by newcomers
5. Redistribute unfair taxation
6. Defend neighbourhoods against other gangs

Their real reason

1. Money
2. Power
3. Revenge
4. Fear and respect
5. Fun and excitement
6. Loyalty to each other and their leader

Their main advantage

1. Secret routes under the city or over the rooftops
2. A rich or connected sponsor
3. Reputation
4. Alliance with other gang(s)
5. Clandestine support from neighbourhood residents
6. They've bribed or intimidated the city guards

Their biggest headache

1. Money-making rackets under threat
2. Powerful enemies
3. Territorial dispute with other gang(s)
4. Loss of safe houses and secret routes
5. Law enforcement crackdown
6. Informant infiltrators