UDK was Unreal 3 based. Prior to that, every AAA engine in existance was expensive, it took some time for that to change and Epic with UDK were part of that cha

UDK was Unreal 3 based. Prior to that, every AAA engine in existance was expensive, it took some time for that to change and Epic with UDK were part of that change. I remember UDK being the first up-to-date (ie not old engines like how id open sourced their old engines) big-name AAA engine that I could download and tinker with for free as a hobbyist.