Basically, yeah. Have your initial "game loop" be a very basic player experience. Have two levels, one to play and test your game mechanics and then the next level is there to test that the game transitions to the second level properly if the first level is completed. Once your "game loop" is working, you can start to "flesh it out" with levels, sounds, music, assets, etc.
I would also recommend archiving your project once you get the basic "game loop" done. This way, if you decide your game needs to be drastically different, you have a fully functional "skeleton" to work with so you're not starting from scratch.