Is it illegal to make a Doom engine game work with Doom user made maps/mods?

[hardcore_gamer]

I know the Doom engine is open source and that making a game using the Doom engine is allowed, but what about user made content that people have made for Doom? Since those maps/mods were originally made for Doom would it be a copyright violation to make your own Doom engine game work with those maps? For example, let's say that somebody made a Doom engine game, and then created some scripts/code that made it so that when user created doom maps are loaded into it it replaces all the textures and enemies with ones from the new game. Would this be ok or would it violate copyright since it allows you to play mods that technically were originally made for Doom rather than the new game? And if it isn't illegal what about advertising? Would it be ok to actually advertise this as a feature for your game by pointing out that Doom mods/levels can work for it?

[snapshot]

https://freedoom.github.io ?

[bonnie]

Gameception is still up, which is a paid app that runs Freedoom by default but allows you to easily download and run other iwads and pwads right from the app, and even explicitly mentions this functionality in the description, but I dunno.

[Nine Inch Heels]

Brutal Doom, despite its name, is probably the closest example to a "doom engine game" seeing how much it has changed about the game's mechanics. In theory it runs with almost every pWAD out there, and that is not "illegal". I don't see how something like a doom engine game being useable on pWADs would be illegal to begin with.

 

From a morality POV, if someone "sells" their doom engine game, and markets it with the benefit of virtually limitless user-generated content available for free from here or elsewhere, it's making money off of someone else's work. Not sure about the legal standards in such a case, but I don't like the way this scenario sounds.

[printz]

54 minutes ago, bonnie said:

Gameception is still up, which is a paid app that runs Freedoom by default but allows you to easily download and run other iwads and pwads right from the app, and even explicitly mentions this functionality in the description, but I dunno.

It's not really up. The author neglected updating it to 64-bit mode, so in effect it won't run on today's Apple devices. I can't find it on the app store from my device, probably for this reason.

 

The price seems minimal and you only pay it once. I guess the author wanted to recover some of his $100 he has to pay yearly just to distribute iOS apps. EDIT: legally the GPL license allows selling, even if other people contributed to the code.