I recently started playing Zelda The Minish Cap (GBA) on my PS Vita, and for me the appeal - especially with old handheld games - is the simplicity in terms of game mechanics.
The game only has like a dozen of equippable items, dialog with NPCs is very simple, there’s a lot of puzzles cleverly integrated into the map, a small trading system (forgot what it’s called, these round things where you match your half with an NPCs half), a few different collectibles (heart containers for example) and they pretty much made a very enjoyable game out of that.
Today, a lot of games come with a crafting system, some sort of hunger/food mechanic, complex character progression systems etc. And while I enjoy this a lot of the time, playing a well crafted game based on much simpler (and fewer) mechanics is a welcome change from time to time.