I'm really happy your nephew enjoys the game, always makes my day hearing that!
I'm currently working on a 2D platformer. It's in the same kind of spirit where there is no dying, just having fun. The biggest difference is that the new game will have dialogue. You can check it out here: https://store.steampowered.com/app/1922800/Whiskered_Away/
It'll be here on Itch.io as well once I release it.
I am also prototyping another 3D Gilbert game but this one has much more realistic graphics and will be a bit different.
(My daughter's older now so I make games that she can enjoy).
Hope that helps. :)