Possibly related to https://itch.io/t/923316/cant-open-mac-osx-10156-19g73#post-2191171, I also can't launch MasterPlan:

  System Version: macOS 10.15.7 (19H15)
  Model Name: MacBook Air
  Model Identifier: MacBookAir8,1
  Processor Name: Dual-Core Intel Core i5
  Processor Speed: 1.6 GHz

ndnd:masterplan-masterplan-mac-release arya$ open -a MasterPlan.app LSOpenURLsWithRole() failed for the application /Users/arya/Downloads/masterplan-masterplan-mac-release/MasterPlan.app with error -10810.

From Console.app:
default 09:00:58.872500-0500 lsd SecTranslocateCreateSecureDirectoryForURL: created /private/var/folders/gb/9rclsj6n3clbzpcv0svycf0h0000gn/T/AppTranslocation/C8C6ADFD-62F0-46D3-A0B9-3A4D27564702/d/MasterPlan.app
default 09:00:59.121500-0500 open LAUNCHING:0x0-0x5116a119 MasterPlan foreground=1 bringForward=1 seed=2683 userActivityCount=0
default 09:00:59.230818-0500 runningboardd [executable<MasterPlan(501)>:15656] Death sentinel fired!
default 09:00:59.244216-0500 loginwindow -[PersistentAppsSupport applicationQuit:] | for app:MasterPlan, _appTrackingState = 2
default 09:00:59.244270-0500 loginwindow -[PersistentAppsSupport applicationQuit:] | App: MasterPlan, quit, updating active tracking timer
default 09:00:59.337461-0500 runningboardd Removing process: [executable<MasterPlan(501)>:15656]
default 09:00:59.338620-0500 runningboardd Removing assertions for terminated process: [executable<MasterPlan(501)>:15656]

Update: It does start it if I run MasterPlan.app/Contents/MacOS/MasterPlan directly.

Hello, thanks for the report and being patient while I work on this. That error code seems to be a generic error code, but seems like it might be arising because the app isn't signed (perhaps?). I'll investigate / see if I can reproduce and fix it for the next bugfix update. Otherwise, I believe the app runs fine through the itch app in the meantime.