OpenSMO (oline srv) is still supported in OutFox 0.4.18.1 LTS

FYI: it is still supported, devs haven’t removed the smo net code, so you can connect to a SMO-based server (if available)
@Jousway recently made a rewrite of it, which is available on Tiny-Foxes. https://github.com/Tiny-Foxes/OpenSMOpp

Also, original OpenSMO (https://github.com/codecat/OpenSMO) looks like abandonware and none of it’s forks is alive.

Indeed. The upcoming LTS 0.4.19 release should improve the experience for OpenSMO players.