DOSBox emulates a full x86 pc with sound and DOS. Its main use is to run old DOS games on platforms which don't have DOS. You can use it to play all PC DOS games.
There is original, somewhat dated original version of DOSBox that You can find on DOSBox Sourceforge page.
Boxer is relying on the DOSBox to work. There’s no clots of configuration and baffling DOS commands between you and your fun: just drag-drop your games onto Boxer, and you’ll be playing in minutes. You can download Boxer from it's homepage.
Dapplegrey gives you the ability to configure DOSBox without having to use the Terminal or edit the configuration file manually. The configuration file, which will be sent to DOSBox, will be written just before Dapplegrey tells DOSBox to start. You can find it here.