[1.13] scaled "join a country's offensive wars" 10 years

[Thineboot]

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# AI
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# War
- No longer willing to join a country's offensive wars if it already joined one from that country in the last 10 years (so they're not just one country's wrecking ball all the time).

While it's a good change maybe you could scale it by provinces or development a country receives or loses due peace treaty.

own_gains = gained development for country and its subjects
AI_gains = gained development for AI-country and its subjects
modifier = AI_gains / (AI_gains + own_gains) ... sign and min/max caps

When a country make gains by joining a country's offensive wars it's more likely to join again and vice versa.

Another possible modifier could be losses of troops and ships.