A very simple launcher (a window with links or buttons that start the games) can be nice to have, but is clearly secondary.
A launcher in Steam style ... with online features? Way too much compatibility and security issues you have to care about, esp. if you want to integrate game features, such as achievements and highscore system.
I say focus on the games instead. On Windows, deploy them using an installer with a nice logo, on Linux in an archive, on MacOS in a nicely designed .dmg.
What each game could do: On its title screen, display an unobstrusive logo or a text hint that it is part of the bundle.