Proton is described as 'tool for use with the Steam client which allows games which are exclusive to Windows to run on Linux kernel and macOS operating systems'. There are more than 10 alternatives to Proton for a variety of platforms, including Linux, Mac, Wine, Windows and BSD. The best alternative is Wine, which is both free and Open Source. Other great apps like Proton are Lutris (Free, Open Source), PlayOnLinux (Free, Open Source), ReactOS (Free, Open Source) and Parallels Desktop (Paid).
Vineyard is a collection of tools and libraries designed to make managing Windows programs on Linux easier. More specifically, it aims to improve the integration of Wine and the Free Desktop and to make it easier to create programs and tools that integrate with Wine.
Using Wineskin technology, Porting Kit is a PaulTheTall.com app that can install games and apps compiled for Microsoft Windows® in Mac OS X. It has access to a server where we store WSI files for more than 300 games, which can be installed by any Porting Kit user.
Run your Windows applications on OSX without the need of buying a Windows license. Well, you even do not need to install Windows. Just download WinOnX and you are ready to go within 2 minutes. No need to install Windows or a virtual machine.
Using bare wine and dosbox usually gives problems when launching a mixture of Windows and MS-Dos applications. Launching a Dos program on Wine sometimes fails, as Wine performs all kinds of custom configurations intended to use Dos programs in particular cases. Represent entire series of exeCute games.