I think this would be a great addition to the selection of games on offer from PortableApps. I understand that we do have a few first-person shooters in the list already, but for something with linear gameplay as opposed to multiplayer focused, I think this ticks a lot of the boxes. The only issue is implementation as it needs either DosBox or some source port to run normally. What does everyone think? Has it been proposed previously?
I think the problem here is that there's no one-size-fits-all DosBox install that works for every system, meaning you could download DosBox Portable (https://portableapps.com/apps/games/dosbox_portable) for freeware games the way you run jPortable (https://portableapps.com/apps/utilities/java_portable) for Java applications. Archive.org for example has a long list of old DOS tools and games available through the browser, but there are a fair number of minor issues with each title where the browser doesn't emulate quite right or the host system is too fast to run the program correctly.
It's a great idea and maybe if someone could work out the bugs, it would be an excellent addition.
Moderator at portablefreeware.com
Sorry to tell you this but the game FreeDoom is just a WAD file. you need a launcher to play it. Try gzdoom or zdoom. (download link is at zdoom.com the software seems to be portable; so you could in theory place it (as well as the freedoom or any doom wads)in the program directory in your Portable apps drive.