Wine is a free, open source application for running Windows software on operating systems that are normally not supported. With Wine, you can install and run these applications just like you would in Windows.
Wine vs CrossOver opinions
It’s free. And you never have to buy anything for wine. You can keep it as long as you want!! And I love that special ability! Thanks!
Lutris is an open source gaming platform for GNU/Linux. It allows you to gather and manage (install, configure and launch) all your games acquired from any source, in a single interface.
PlayOnLinux is a graphical frontend for the Wine software compatibility layer which allows Linux and Mac users to install Windows-based video games, Microsoft Office (2000 to 2010), Microsoft Internet Explorer, as well as many other applications.
PlayOnLinux - PlayOnMac vs CrossOver opinions
Pegasus is a graphical frontend for browsing your game library (especially retro games) and launching them from one place. It's focusing on customizability, cross platform support (including embedded devices) and high performance.
A front-end or user interface (UI) is the presentation and interaction layer of an app or website. Most modern emulator apps have basic game list UIs that you can interact with using a mouse/keyboard but not a game controller.