According to the Kickstarter page, "Play Tonics" will allow you to modify the game however you'd like...
Does anyone get a "Cheat" vibe from this? Like these are going to be the equivalent of collecting Cheato pages? If so, then I like the idea, especially if it's completely optional. If you want, you can make the game easier through these Play Tonics, but if not, then you can just as easily ignore them or turn them off once you've activated them, just like the Cheats in Banjo-Kazooie and particularly Banjo-Tooie.
For development "Twoka-Laylee", please watch these:
For everyone else, talk about these videos !