I've successfully gotten the venerable Radar Contact V4 offline ATC program working with XP12.  For those that aren't aware, Radar Contact was a payware ATC product created by a collaboration between an FAA air traffic controller and a programmer (Doug Thompson and John Dekker) for the ESP-based sims (FS9, FSX, P3D).  The developers ceased development some time back, and in so doing generously left the program to the community as freeware (available from the AVSIM library).  For IFR point-to-point flights, it's still my favorite for providing a realistic ATC radar service, with very good attention to phraseology and procedures.

In conjunction with a couple of utilities, RC4 does run with X-Plane 11 (I use it with XP 11.55r) and, as luck would have it, with X-Plane 12.00 (release).

The RC4 program and a key generator for it are available from the AVSIM library.  We also have a dedicated user-to-user support forum here on the AVSIM forums.

To run it with X-Plane (11 or 12) you'll need to track down a copy of XPUIPC v2.0.5.9--this freeware utility emulates a subset of the IPC interface of the popular FSUIPC program used with the ESP sims.  It installs as a plugin for X-Plane.

In addition, you'll need a utility called Makerwys for XPlane (V1.2, or later if a new version emerges). 

You'll also need a ~$20 add-on made by FS++ (the makers of Multicrew Experience) called RC4toXPlane, which enables the RC4 menus to work inside a window in X-Plane.  FS++ recently re-compiled the program with the new XPLM libraries for X-Plane 12.  If you're already using an older version, you'll want to download the new one from your account page at SimMarket before trying to use it with XP12.

There are a couple caveats for making RC4 work with XP12, however.

First, Makerwys for X-Plane was last updated in 2016 and the author appears to have left the hobby.  The program crawls through your X-Plane scenery configuration to create a data file called r4.csv, used by Radar Contact to identify the airports/runways around the planet.  Unfortunately the utility, as it stands now, does *not* work with XP12--the file structure and most likely the dsf file format have changed in XP12, rendering the utility inoperable.  Currently, though, the XP11 and XP12 airport databases are pretty close to identical, so you can run Makerwys on a copy of XP11 and point Radar Contact to your XP11 main folder for a database build, and it will populate its database from the XP11 dsf folders, which, for now works in the vast majority of locations.

Second, XPUIPC is also a legacy/unsupported utility whose author has apparently left the field.  It still works with the release version of XP 12.00, but it is now throwing warnings about around 20 old datarefs that have had their names changed.  Presently XPUIPC 2.0.5.9 still works, but at some point LR is likely to deprecate (do away with) the old datarefs, and that will require either a re-write of XPUIPC or some other alternative solution.

Still, at present it's a pretty good ATC option for the IFR sim pilot in XP12.

An addendum--you'll also want to add these three lines to your XPUIPCOffsets.cfg file to compensate for XP12's altimeter temperature error simulation, otherwise ATC will be yelling at you for being off your altitude a lot.

Dataref	Ht_m	sim/flightmodel/position/elevation	double
Dataref	Ht_temp_corr	sim/weather/aircraft/altimeter_temperature_error	float
Offset	0x0574	SINT32	1	r	$Ht_m $Ht_temp_corr 0.3048 * + 0.5 + round

 

Great, thank you for a heads up.

Your post actually reminded me about fiddling with PFE ATC in XP11, using PFEtoXplane plugin. Same principle, different ATC app.
In general it works fine, except one little thing - it can't read ActiveSkyXP injected weather (metar data). It seems it only read XP11 weather data, as it most of the time will give you wrong takeoff/landing runways. One "solution" is to disable specific runways on departure and arrival airports in the PFE options, and that will work ONLY in the case that the wind isn't changed on both departure and arrival airport during the pre-flight/enroute. Also, it requires XPUIPC, and that plugin alone causes issues with Traffic Global, causing AI to fly at 90kts on cruise, too low, etc etc. I would rather fly with proper AI, to see the sky alive, than to fiddle with ATC with a requirements to setup the flight with disabling runways. Too much work just to prepare for a single flight.