Most of the systems played at UK Armageddon are indoor only systems. The main focus of Armageddon has always been the indoor systems and will continue to be so. It is generally felt that indoor systems offer a much greater level of uniqueness compared to each other, while most outdoor systems play in a very similar way.
Outdoor systems have been used on a number of occasions from a variety of manufacturers. The format used has changed each year when outdoor has been used based upon field operator recommendations.
As a result there is no official format used for UK Armageddon, and Outdoor is generally not regarded a core system.