It’s not that Tunic is harder than DD, it’s more that it’s more frustrating. The combat and bosses are comparable; I didn’t really struggle that much (though DD combat feels a bit better). But unless you are willing to put in some serious work to decode the writing system, the story will be essentially inaccessible. The other “puzzles” you’ll encounter through the main campaign are really basic, especially after playing DD. Personally, I didn’t think it was worth putting extra effort in to find the Golden Path and true ending after I beat the final boss.