This Application is dedicated for running Multiple games through steam, Allowing the possibility to run Multiple Mods for Terraria at one given time.
It also allows you to run via command prompt or in GUI mode. Opposed to the other Launchers, this application runs faster and is by far more flexible for users. Within the program users can monitor what is currently playing and are even able to generate new GLI files accordingly (Even outside the steam folder!).
Untested, But it should be also possible for any game to be launched like this, not just Terraria, With or without Steam.
To use TLauncher download the executable 'TLauncher.exe' in the 'TLauncher/bin/Debug' directory and place in the Steam folder as Terraria.exe. Some mods will require Terraria to be a certain name, so be sure to rename it accordingly. But most times if coded correctly it should search for the asembly itself. Next you would want to start Terraria through steam, and wait for the GUI to start.
Note: When starting Terraria, it is normal for it to take a while, It's loading content.