There never was a lotus improv for non NeXT hardware. Lotus killed NeXT improv basically lay immediately after it came out.

What happened was lighthouse design came in and built an exact clone of improv called quantrix. The manuals were interchangeable - I’m actually learning them now.

I bought a boxed copy of improv and quantrix manuals. It is /excellent/ we really have a lot of excellent ideas in our computing past.

If you want a copy of the lighthouse apps (they gave away licenses when sun bought them in 1996 or so. ) check out next computers.org They have a file section.