Simsig is really fun IMO. There are quite a few free maps, some more complicated than others, and some paid for.
I’ve not played it in a while, but I’m a fan of the Huddersfield map as it has a mix of different types of signalling as it extends out to Diggle Junction.
Agreed!
I haven't played it for a while, but I also enjoyed messing around with SimSig. I started off with one of the single-line Welsh routes but I got bored quite quickly. Eventually I discovered Carlisle, which is fairly easy to handle as a single player. Well, it was until I tried the late 70s/early 80s timetable that required loco changes from diesel to electric and vice-versa, along with the required moves from depots...
Those were free routes, but I did spend some money and bought the Edinburgh sim, which includes the Caledonian Sleeper shunts (bring your own Valium)! I also bought the east Scotland route, which covers Perth, Dundee, Aberdeen and places inbetween, many of which were controlled by mechanical boxes; this is definitely not one that you want to tackle on your own unless you're a) very, very good at multitasking or b) insane!
Try one of the free routes in order to get the hang of the mechanics of it, and if you have other people who are interested, you can either play a more complicated sim and divide the tasks between you, or you can "chain" a few different sims together to cover a larger area.