Simsig a million percent. The actual signalling experience is pretty realistic. The only thing really missing is stuff like line blocks, possessions, engineering work (etc), though if keen you can simulate that yourself.
Line blocks can be put in place in a way which, as per the VDU setup in an IECC, will make the track turn blue.
Assuming you have a Windows setup, press F11 which brings up an Incident Control Panel (see ss_icp.jpg). Click the "Track Sections" tab which will bring up a list of all the track sections in the sim you are using. Click on the small mouse icon at the top right of the list and then click on a track section in the sim. Then, in the ICP, click the dropdown list under "Isolations" and from that menu select ENG. This will turn the track blue and any attempts to set a route on the blue track sections will not succeed. The track may not turn blue but even if it doesn't the non-blue track section will still behave as if blocked making route setting impossible. Any isolated (ENG-covered) track sections will highlight in the list of track sections in the ICP.
To lift the block on a blue bit of track the process is the same but select "None" from the isolations menu and the blue, if it is there, should disappear: on a non-blue track section with an ENG isolation the effect will be the same though and as any isolated (ENG-covered) track sections will highlight in the list of track sections in the ICP the process should be a bit less time consuming because you can click on the TS in the list and select "None" from the Isolations menu.
Unfortunately you have to repeat this process for each track section you wish to block / unblock which makes it time consuming: you cannot select multiple track sections at a time.
If all goes well with imposing a block then you should have a situation as demonstrated in the screenshot which is also attached to this post: using the above method I put a line block in platforms 3 and 4 of
Crewe the simulation of which, covering the whole Crewe area, was released on Monday (17th April): it is a complex sim covering Crewe station and all the fringe boxes (Salop Goods Jcn, Basford Hall, etc.) which has been sometime in the making but it is also the most expensive one on SimSig.
HTIOI,
Dave