AfterStep is a window manager modelled after the NeXTStep interface.
I've built AfterStep for Solaris and made the packages available. These packages include aterm, the AfterStep terminal emulator.
Choose the right file from the following list:
To install,
pkgadd -d PCTafterstep.i386.pkg PCTafterstep
where you should replace "PCTafterstep.i386.pkg" with whichever file you downloaded.
(Using pkgadd should work on OpenSolaris distributions too. You can safely ignore any conflicts marked as "attribute change only". And binary compatibility should ensure that the software works correctly as well.)