I too wrote my own platform, in the early 80s, in C++. I didn't use C++ for the user-written code, instead I used a Forth like, implemented in C++. This probably doomed the program, along with my inability to get string literals and vehicles such as boats right. But it was a great intro to C++, and I spent some time writing an easy, story-telling game, based on Jack Vance's Dying Earth books, in it.

Time is never wasted when you are doing something new.