LR-87 is a fun Gemini client implementation written entirely in Fortran and available for most any system with a modern Fortran compiler. Two renderers are available in source code:
LR-87 does not support client certificates because... well, it doesn't. That doesn't really seem to be much of a problem at this time, though, aside from some gimmicky sites.
LR-87 can be compiled from source if you visit:
or, alternatively, you can download this snapshot
But if you want a binary...
LR-87 is available as a Snap:
snap install lr87
It will not be distributed any other way because it is a chore otherwise.
LR-87 is available in the Windows Store:
An unsigned executable is available below:
I'm considering a Windows Store submission, but I'm not sure it works well enough for that.