Multiplier when island have 2 or more players

[Pepek94]

Description

Is your feature request related to a problem?

Nope

Describe the solution you'd like us to implement.

I would like to introduce a multiplier requirements for islands with many players.

Describe alternatives you've considered.

example.
Multiplier: 1
Island with 1 player: 100
Island with 2 players: 200
Island with 3 players: 300

Multiplier: 0.5
Island with 1 player: 100
Island with 2 players: 150 (100 * 0.5) + 100
Island with 3 players: 225 (150 * 0.5) + 150

Additional context