Bioshock 2 Remastered - derrod/legendary GitHub Wiki
By default Bioshock 2 Remastered will launch the 2K Launcher, which will not recognise Bioshock 2 Remastered as being installed. Worse yet, even if it did it would try to run the Epic Launcher again. To work around it you can override the executable Legendary will launch via the config or command line:
Command line
legendary launch b22ce34b4ce0408c97a888554447479b --override-exe Build/FinalEpic/Bioshock2HD.exe
Config
[b22ce34b4ce0408c97a888554447479b]
override_exe = Build/FinalEpic/Bioshock2HD.exe