The reasons I decided to stop working on Pong before it was completely polished include
I had been working on MPong for so long that it was tough to find the motivation to continue working on it.
Although, I was continuously adding features to the engine, I was not building up my portfolio.
I wanted to test my engine with another game and see how much of the code is reusable.
What Went Right
Engine Components: Starting with Pong as my first game, made me concentrate on the engine part. I managed to create a fair amount of the modules I had initially aimed for. Most of the modules were reusable.
Setup: I managed to come up with a relatively painless way of setting up new projects.
Re-factoring: I was quite happy with how the codebase was at that point (all things considered). The fact that I was continuously refactoring the code, was beneficial.
Commenting: I managed to comment a lot of my classes while programming.
Using a Repository: Having a repository for my code, meant that I could revert any bugs that I introduced without having to waste too much time.
What Went Wrong
Missing Engine Components: I did not get a chance to work on the physics and networking modules.
Switching to DirectX 11: In the middle of the project, I decided to switch to DirectX 11 from DirectX 9. I ended up fixing a lot of bugs that got introduced because of the difference in the way things are handled between the two.
Engine Code as part of Project: The engine setup and repository was closely tied to the Pong Project. I should have taken out the engine components and made it into a separate repository and solution, so that it was easily reusable.
Not Setting a Deadline: The fact that I did not have a deadline in place, meant that I took my own sweet time to make the game. This has resulted in Mpong being in development for a very long time, without me having to show much for it.
Switching to an Obsolete Technology: I decided to use DirectSound for my SoundEngine. It was only after I had implemented a fair amount of code that someone pointed out to me that I should have used XAudio instead
Things I wish I had Implemented
Physics and Networking modules
Support for 2D game elements.
High Score Table
Pause on Minimizing