The strange 'when' keyword was just a macro for break;case pair which I think is cute. I may even keep that macro, but some macros may have to go. Oh, I'm talking about Banana Rogue, a derived game from Advanced Rogue. I've now gone through source files and mostly created missing header files. Somehow it was possible to compile the source without header files back in what year it was made, because they weren't missing from the source, otherwise there would have been #includes for them, right?
The year is also a mystery (well, guess I could google more about it...) because the source says it's 1985, but it can't be that early, right? Also, the xcrypt source code which is some kind of strange encrypting method for wizard's password is from 1994. I think 1990's is much better guess for this game, they just didn't put it into the source code, but kept some random year, maybe the year they started to work on this game.
Xcrypt can be removed, because it's used for networking (password) which is going to be removed also. The system they programmed this had some kind of built-in networking, this was I think before widespread use of internet as we know today.
What is quite surprising is how clean the source code actually is. There aren't too much parameters in functions and the game has only few datatypes. Probably the most dangerous one is the linked_list which is as mentioned before a linked list type and when you combine C's memory management to that it could be a source of bugs. It's maybe too big task to replace it with C++ version, but it's early to tell. Maybe the internal implementation can be changed.
I'm not too concerned about "destroying" the original source code, but at the same time it's silly to replace everything that looks "bad" from C++ perspective.