There are 5 scenarios in the Suryavarman I campaign:
1. Usurpation
2. Quelling the Rebellion
3. A Dangerous Mission
4. Challenging a Thalassocracy
5. Nirvanapada
Win every scenario of the campaign using the cheat code “i r winner”. Then, to trigger the achievement, win any scenario of any campaign without using cheat codes. The quickest scenario is the 1st scenario of the William Wallace Learning Campaign: Marching and Fighting.