I doubt this is intended behavior, but hitting "new game" by accident erased all my progress, even though I immediately quit the game without saving.

You can not start a new game without erasing the old games progress. This is just one of my many issues this game got, along with excessive CPU usage. To me, the game is technically not in a shape i can further allow it in my collection with a straight face... so, i was removing it. If the game gets updated and polished at some later point i may play it again.