On our browser game we have hundreds of players that interact with each other. One thing we've learned is that the majority of players don't like to battle that much. They just stay in their planets, making new facilities and combat units, and growing in richness and power. But what use is it to have so many combat units hanging around? They feel protected that way and won't engage war unless provoked.
So, how to make the players engage combat? We came up with the concept of Relics. A relic is a special artifact on the universe map that alliances can conquer, control and defend. A relic provides all alliance members with rare resources income, and it's better for alliances to get as much relics as they can manage.
On this image we have a Relic on the center, and a protection ring, with a lot of battles at that moment. Because the relics generate so much income, alliances focus on conquering as much relics as they can. The search for relics was so much that we even implemented additional alliance collaboration features.
So, this turned out to be a success. And this is the best way we can for the game design of the game, learning from the experience and implementing new features as the game progresses.