I’d think it’d be really cool if a Minigolf Course directly based off of Doom’s “Knee Deep in the Dead” and Quake’s “Dimension of the Doomed” was a thing, Doom being the first half and Quake being the second. Of course, you’d probably have to get id’s permission and all if such a thing’s going to be implemented, but I don’t imagine it’d be too hard to do.
Much of the hard work getting the maps in would be reduced too, given that most of the course has already been made, and all that really needs to be done is to make it more like an actual minigolfer course (e.g bumpers and walls in the right places to prevent the ball from getting too off-course and tubes to bring the ball upstairs, et al.) than a normal FPS level with a Minigolf Ball & Flag in it.
Of course, it would be limited to the shareware levels, but 17 levels is a pretty good amount of holes for a course, especially since they’re the only levels that can be freely distributed and, say, turned into a Minigolf course.
I don’t think it’d be all that likely, given copyright’s a fickle thing, but it would be really, really cool if it happened, especially if id makes a special 18th hole just for this course.