It looks like yesterday's post on HARP got some wheels turning, as evidenced by this post at Stargazer's World and this one at Dungeon Mastering 101 (look at us, leading a mini-mini-revival)!
So what happened to HARP? A few years back, it was what seemed to be selling for Iron Crown. There were solid supplements, good support, and all in all, it seemed to be at least a mild success. So did ICE's support dry up, then talk about the game? Or did the game peter out, followed by ICE's support for it? OR (perhaps most likely) was it just that ICE is large enough for one supported line at a time, and Rolemaster Express and the Rolemaster 2 revival was the new (old) hotness?
I don't claim to have answers, and I haven't dug too deeply, but it occurs to me that HARP might be a case study for many d20 alternatives that make noise for a bit, only to quiet down to a mere murmur.