Unplayable on Catalina: fullscreen game flickers horribly or windowed game cannot tag tiles

Hello, I have War for the Overworld on Steam. I haven't played in a year. Last had played on Windows. Wanted to play again. Installed on my MacBook Pro, but...

In fullscreen mode, all overlay graphics quickly start flickering between random screen positions and sizes making the menus unusable and the game unplayable. However, I can tag game tiles.

In windowed mode, graphics work perfectly fine. However, 95% of the time I cannot tag game tiles, making the game unplayable. The menu overlays work. If I repeatedly zoom in and out and scroll around, I can rarely tag a tile to be dug.

So, either I can barely see the game or I can barely control the game. Is there a fix for this, or at least a work around such as command line arguments?

Game: War for the Overworld V2.1.0f4 through Steam

Model Name: MacBook Pro (15-inch, Mid 2012)

Model Identifier: MacBookPro9,1

Processor: 2.7 GHz Quad-Core Intel i7

Memory: 16 GB 1600 MHz DDR3

Graphics: NVIDIA GeForce GT 650M 1 GB (on PCIe)

Graphics: Intel HD Graphics 4000 1536 MB (built-in)

Display: 15.4-inch (1680x1050, non-glossy)

OS: macOS Catalina, v10.15.7, fully updated

I just performed a clean install of Catalina on my MacBook Pro, and it is the final supported macOS for this machine.

I have also added a dual boot through Boot Camp of Windows 10 22H2, fully updated. The same game is very playable when I boot into Windows 10, however, I'd prefer not have to reboot just to play.