Morse Runner is a Windows-based contest simulator developed by Alex Shovkoplyas, VE3NEA. Using Wineskin, it has been successfully and seamlessly run under OSX, and made available here for download. Sure, you could use Wineskin to do this yourself (and save me some bandwidth), or you can pull the ready-made dmg from here.
Running Catalina? Go to 'Download' to read the latest (and grab a box of tissues)

Speak it softly, and you stitch a seam. Say it loudly, and you summon a chorus. Either way, "isaidub" is no longer merely ink on a file. It is a living node in the town’s long, messy map of remembrance—proof that when names shift, the dead keep rearranging the rooms of the living.
In the town where every street echoed a different year, the murders arrived like weather: sudden, unannounced, inexplicably patterned. Newspapers, hungry for meaning, printed sketches stitched from rumor. The living stitched up the dead with their own versions of grief, each narrative a patch over the same wound. Somewhere between whispers and headlines, a fragment took shape: "isaidub." memories of murders isaidub
At first it was nothing but a grain in the mouths of children playing where police tape used to flap. Then a barroom joke—half-remembered, half-true—until a retired typist found it in the margin of an old case file: a single, lower-case scrawl: isaidub. No spaces, no punctuation. The typist pressed her thumb to the ink and felt the paper shiver as if it had something to confess. Speak it softly, and you stitch a seam
In the archive now, the phrase sits on a yellowing card between a photograph of a porch swing and a list of names. Scholars call it a keystone of oral culture; the locals call it an old joke that never quite stops being funny. The murders are still unsolved in the sense that the ledger never balances. But the town has learned another calculus: that memory, like language, is how people arrange their losses into something survivable. "I said dub" is neither verdict nor absolution; it is a way to keep speaking on behalf of the vanished. It is a living node in the town’s
Confirmed working on: El Capitan, Mavericks, Sierra, High Sierra, & Mojave
MANY reports that it DOES NOT work on Catalina. It is very unlikely that it will work under Catalina in the near future, as it would require some pretty hefty development on Wine (they're working on it). The only other option I see is for some nice macOS developer to take the original code (it's open source!) and re-write it to run natively on 64bit macOS (go ask any developer, this is a lot of work). Since Xcode is now free if you're running Catalina, I'm happy to give it a try... when I can afford to buy a system that can run Catalina :)
If you have questions or comments about using this application under OSX, please email them to ki4stu k4iz at arrl dot net.