The premium currency in Rise of Civilizations is gems and there are several different ways that you can obtain them free during gameplay, some of which are listed below.
• Daily Quests
• Primary Quests
• Cave Exploration
• Barbarian Hunting
• Server Wide Monument Achievements
• Events and Special Giveaways
• Linking your Game
Simply link your game to your Google Play or Facebook account.
• Write Review
If you click 'yes' when asked if you are enjoying the game you will be prompted to writes a review (you will still get gems even if you don't write one).
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