After a few adjustments and changes here and there, I ended up with a prototype that was making me happy. So I could move forward.

The next step before leaving pre-production and entering full production was to create a vertical slice.

Vertical slice is a small piece of your game, playable, that allows you to see everything of the game working together. It's the final test that tells you if it's really worth it, fun, interesting, etc.

So vertical slice unlike prototype, it includes assets, music, animations...

Once the vertical slice was completed I could move into production.