I didn't know it's possible to get UnrealED4 by buying RoboBlitz. Additionally, I didn't know RoboBlitz using UnrealEngine is sold through Steam. Because Steam is managed by Valve which sales Source Engine, that's an interesting situation.
However, these days, Valve's software doesn't run well on my XP. I have not understood the cause. I can't play Half-Life2 and use Hammer. So I'm just wondering whether to buy RoboBlitz by $15.