TailQuest Defense looks like one to pop on your wishlist. After 5 years in development from a two-person team in Godot Engine, a demo is up now.
It's a tower defense game, that also blends in some exploration and puzzles. Featuring colourful graphics, family-friendly gameplay, puzzles, platforming and plenty of secrets to discover that you can also play in co-op it has a lot of elements that could make it a winning combination.
See their original trailer below:
Not only does it offer up Native Linux support, the developers are long-time Ubuntu users too.
If you do give it a go, let us know in the comments what you think about it.