Probably one of the projects I've been following as religiously as OpenXcom is Freesynd, but boy do they take time between releases.
https://freesynd.sourceforge.net/For those who don't know, Freesynd is to Syndicate what OpenXcom is to the original X-COM: an open source engine re-implementation. I love the original Syndicate, but I also acknowledge it has always been a deeply flawed and partially incomplete game, with shitty AI, unpolished gameplay and, for some reason, no interior graphics whatsoever. The sheer brutality and fast pacing of Syndicate is what made it so great, along with the awesome industrial cyberpunk setting. But now, fortunately, there's Freesynd, restoring the hopes that someone, some day, might actually pick it up and use it to rebuild Syndicate as the game it always deserved to be.
The aim of the current team is to have everything up and running at 1.0 and only then start adding improvements, but since they can take YEARS before releasing an update, it might still be a long time before we see a proper advancement of classic Syndicate. As of 0.7, there's still a lot to be fixed and implemented as the game still isn't completable at all. And remember kids, you need and original copy of Syndicate, (which can be purchased
here, for what I consider to be a more or less unfair price) in order to play Freesynd.